single-stage isoflow ™ absorption liquid chillers manual/yia_spec_engineeringguide.pdf ·...

OPERATING AND MAINTENANCE INSTRUCTIONS

SINGLE-STAGE ISOFLOW ™ ABSORPTION LIQUID CHILLERS

New Release Form 155.16-OM1 (1200)

MODELS YIA 1A1 THROUGH YIA 14F3

00101VIP

Section 1 INTRODUCTION......................................................................................................6

GENERAL................................................................................................................6NOMENCLATURE..................................................................................................6

Section 2 ABSORPTION SYSTEM OPERATION ................................................................7

GENERAL INFORMATION ..................................................................................7Evaporator..............................................................................................................7Absorber ................................................................................................................7Generator ..............................................................................................................7Condenser ..............................................................................................................7

DESCRIPTION OF MAJOR COMPONENTS AND SUB-SYSTEMS................9General Condenser Shell Assembly......................................................................9Evaporator-Absorber Shell Assembly ..................................................................9Solution Pump ......................................................................................................9Refrigerant Pump ..................................................................................................9Heat Exchanger ....................................................................................................9Purge System ........................................................................................................9Controls and Wiring ..............................................................................................9

CONTROL DESCRIPTIONS................................................................................10Components in the Control Center ....................................................................10Components of Power Panel ..............................................................................10Components External to the Control Center ......................................................12

CONTROL SEQUENCE ......................................................................................14SYSTEM OPERATION ........................................................................................16

General ................................................................................................................16CAPACITY CONTROL ........................................................................................19

General ................................................................................................................19Maximum Load Limits at Reduced Condensing Water Temperatures ..............19Solution and Refrigerant Interchange During Operation ..................................19Anti-Freeze Line..................................................................................................22Chilled Water Control Stability ..........................................................................22Stabilizer Refrigerant Solenoid (2SOL)..............................................................22Capacity Control Valve Override........................................................................22Automatic Decrystallization Control ..................................................................22

DISCUSSION OF SUB-SYSTEM OPERATION ................................................22Automatic Decrystallization Feature ..................................................................22

Basic Automatic Decrystallization Piping Circuit – Model YIA, All Sizes ..23ADC Flush Line ................................................................................................23Combination of Basic ADC Piping Circuit and ADC Control Feature ..........232SOL – Refrigerant Valve Blowdown..............................................................24

Section 3 PURGE SYSTEM OPERATION ..........................................................................26

GENERAL..............................................................................................................26FUNCTION ............................................................................................................26SYSTEM DETAILS ..............................................................................................28

YORK INTERNATIONAL

TABLE OF CONTENTS

2

FORM 155.16-OM1

3YORK INTERNATIONAL

Section 4 PURGE PUMP OPERATION ................................................................................29

GENERAL..............................................................................................................29Cleanliness ..........................................................................................................29Types of Lubricants ............................................................................................29

PURGE PUMP PIPING AND OPERATING VALVES........................................29The Principle of Gas Ballast ..............................................................................29

OIL LEVEL DETERMINATION..........................................................................29

Section 5 PURGE PUMP MAINTENANCE ........................................................................30

VACUUM PROBLEMS ........................................................................................30Pressure Determinations......................................................................................30Oil Contamination ..............................................................................................30

OIL CHANGES AND OIL LEVELS....................................................................30Draining The Pump ............................................................................................30Flushing The Pump ............................................................................................30Refilling The Pump ............................................................................................31

SHAFT SEAL REPLACEMENT ..........................................................................31REPAIRING OIL LEAKS......................................................................................31

Location, Cause and Effect ................................................................................31Repairing Technique............................................................................................31

DRIVE PROBLEMS..............................................................................................32

Section 6 BUFFALO PUMPS ..................................................................................................34

INTRODUCTION ..................................................................................................34TROUBLESHOOTING ........................................................................................34

Pump Tripping On Overloads ............................................................................34Pump Tripping On Thermal Protection ..............................................................34Unusual Noise/Vibration ....................................................................................34Pump Overhaul ....................................................................................................34

Section 7 STEAM AND WATER QUALITY CONTROL ..................................................36

GENERAL ................................................................................................................36STEAM/CONDENSATE OR HOT WATER QUALITY ........................................36TUBE CLEANING....................................................................................................37

Section 8 UNIT OPERATING PROCEDURES ..................................................................38

GENERAL..............................................................................................................38START-UP (NORMAL) ........................................................................................38SHUTDOWN (NORMAL) ....................................................................................39

Manual Shutdown................................................................................................39OPERATING DATA ..............................................................................................39

General ................................................................................................................39Performance Data and Calculations....................................................................40

YORK INTERNATIONAL4

Section 9 PTX CHART ............................................................................................................42

READING THE PTX CHART..................................................................................42CRYSTALLIZATION................................................................................................42PRESSURE DROP CURVES....................................................................................45REFRIGERANT CONCENTRATION ....................................................................45

Section 10 PREVENTATIVE MAINTENANCE ....................................................................57

CLEANING AND MAINTAINING THE TUBES WITHIN THE SHELLS ........57Tubes ......................................................................................................................57

BRUSH CLEANING OF TUBES ............................................................................57TROUBLESHOOTING TABLE ..............................................................................58PREVENTATIVE MAINTENANCE SCHEDULE ................................................59

APPENDIX

Glossary Of Terms..................................................................................................61

LIST OF ILLUSTRATIONSFig. 1 – Basic Cycle Diagram ......................................................................................................................8Fig. 2 – Typical Power Panel......................................................................................................................11Fig. 3 – Model YIA Absorption Unit, Front View ....................................................................................13Fig. 4 – System Control Components Location ........................................................................................15Fig. 5 – Evaporator ....................................................................................................................................16Fig. 6 – Absorber........................................................................................................................................16Fig. 7 – Solution Pump ..............................................................................................................................16Fig. 8 – Generator ......................................................................................................................................16Fig. 9 – Condenser......................................................................................................................................17

Fig. 10 – Cycle Diagram (Hot Water Units and Steam Units) ....................................................................18Fig. 11 – IsoFlow Absorption System Solution Concentration Average in System Solution Circuit ........19Fig. 12 – Solution and Refrigerant Level Variation With Load ..................................................................20Fig. 13 – Automatic Decrystallization Feature (Hot Water Units & Steam Units with ADC Control) ......25Fig. 14 – Bubble Testing for Leaks..............................................................................................................26Fig. 15 – IsoFlowTM Purge System ............................................................................................................27Fig. 16 – Purge Drum Details ......................................................................................................................28Fig. 17 – The Complete Purge System ........................................................................................................28Fig. 18 – Purge Pump Piping & Valves - Normal Operation ......................................................................29Fig. 19 – Model 1402 Vacuum Pump for YORK ........................................................................................33Fig. 20 – Flow of Refrigerant Water or Lithium Bromide through Pump ..................................................35Fig. 21 – Acceptable Unit Internal Pressures ..............................................................................................38Fig. 22 – Operating Data Sheet ....................................................................................................................41Fig. 23 – PTX Chart ....................................................................................................................................43Fig. 24 – Pressure Drop Curves ..................................................................................................................46Fig. 25 – Pressure Equivalents ....................................................................................................................65Fig. 26 – Vacuum Units of Measurement ....................................................................................................65Fig. 27 – Complete Cycle Diagram..............................................................................................................67

FORM 155.16-OM1

5YORK INTERNATIONAL

IMPORTANT!READ BEFORE PROCEEDING!

GENERAL SAFETY GUIDELINES

This equipment is a relatively complicated apparatus.During installation, operation, maintenance or service,individuals may be exposed to certain components orconditions including, but not limited to: refrigerants,oils, materials under pressure, rotating components,and both high and low voltage. Each of these itemshas the potential, if misused or handled improperly, tocause bodily injury or death. It is the obligation andresponsibility of operating/service personnel to identi-fy and recognize these inherent hazards, protect them-selves, and proceed safely in completing their tasks.Failure to comply with any of these requirementscould result in serious damage to the equipment andthe property in which it is situated, as well as severe

personal injury or death to themselves and people atthe site.

This document is intended for use by owner-author-ized operating/service personnel. It is expected thatthis individual possesses independent training thatwill enable them to perform their assigned tasks prop-erly and safely. It is essential that, prior to performingany task on this equipment, this individual shall haveread and understood this document and any refer-enced materials. This individual shall also be familiarwith and comply with all applicable governmentalstandards and regulations pertaining to the task inquestion.

SAFETY SYMBOLS

DANGER indicates an imminentlyhazardous situation which, if notavoided, will result in death or seri-ous injury.

CAUTION identifies a hazardwhich could lead to damage to themachine, damage to other equip-ment and/or environmental pollu-tion. Usually an instruction will begiven, together with a brief expla-nation.

The following symbols are used in this document to alert the reader to areas of potential hazard:

WARNING indicates a potentiallyhazardous situation which, if notavoided, could result in death orserious injury.

NOTE is used to highlight addition-al information which may be help-ful to you.

CHANGEABILITY OF THIS DOCUMENT

In complying with YORK’s policy for continuousproduct improvement, the information contained inthis document is subject to change without notice.While YORK makes no commitment to update or pro-vide current information automatically to the manualowner, that information, if applicable, can be obtainedby contacting the nearest YORK Applied SystemsService office.

It is the responsibility of operating/service personnelas to the applicability of these documents to the equip-ment in question. If there is any question in the mindof operating/service personnel as to the applicabilityof these documents, then, prior to working on theequipment, they should verify with the owner whetherthe equipment has been modified and if current litera-ture is available.

YORK INTERNATIONAL6

GENERAL

This manual contains instructions and information re-quired by the operator for proper operation and preven-tative maintenance of the YORK IsoFlow AbsorptionLiquid Chillers.

Included in this instruction are discussions of the basicprinciples of operation of Lithium Bromide AbsorptionSystems and descriptions of the functional operation ofmajor components and sub-systems. Instructions relat-ed to the controls and normal operating sequence of thevarious modifications of the IsoFlow units can befound in Form 155.16-O3 "Operators Manual –Control Panel" and Form 155.16-N3, “IsoFlowInstallation Manual”.

Procedures and checks to be conducted by the operatorare described extensively for all areas of operation.These involve the Pre-Start modes of units, normal op-eration of units and operational functions related togeneral performance of the system. Information andguides are given pertaining to care and general mainte-nance of the unit.

SECTION 1 – INTRODUCTION

NOMENCLATURE

A system of nomenclature used for identification pur-poses of Model YIA Absorption Chillers is describedas follows.

It is imperative that the operator knowthe designation of any given unit in-tended to be operated in accordancewith this instruction; this is necessaryto ensure that the appropriate sectionsof this manual are applied. The unitdesignation can be determined fromthe unit data plate on the side of thecontrol panel. The unit serial numberis also shown.

NOMENCLATURE

The model number denotes the following characteristics of the unit:

YIA – ST – 8E1 – 46 – B – S

UNIT TYPE SPECIALYORK IsoFlow Absorption Chiller Special Tubes

Contract Job

HEAT SOURCE DESIGN LEVELST = SteamHW = Hot Water VOLTAGE CODE

17 = 208-3-6028 = 230-3-60

UNIT SIZE 46 = 460-3-601A1 through 14F3 50 = 380-3-50

58 = 575-3-60

FORM 155.16-OM1

7YORK INTERNATIONAL

SECTION 2 – ABSORPTION SYSTEM OPERATION

GENERAL INFORMATION

The principle of refrigeration is the exchange of heatand, in absorption liquid chilling, there are four basicheat exchange surfaces: the evaporator, the absorber,the generator and the condenser. Refer to Figure 1.

In absorption chilling, the refrigerant is water but, likeany refrigeration system, absorption chilling uses evap-oration and condensation to remove heat. To maintaineffective evaporation and condensation, absorptionchilling employs two shells which operate at different,controlled vacuums.

The lower shell (Evaporator and Absorber) has an in-ternal absolute pressure of about one one-hundredththat of the outside atmosphere - or six millimeters ofmercury, a relatively high vacuum. The vacuum allowswater (the refrigerant) to boil at a temperature belowthat of the liquid being chilled. Thus, chilled liquidentering the evaporator can be cooled for air condition-ing or process cooling applications.

Evaporator

Refrigerant enters the top of the lower shell and issprayed over the evaporator tube bundle. Heat from theliquid being chilled evaporates the refrigerant.

Absorber

The refrigerant vapor then migrates to the bottom halfof the lower shell. Here, the vapor is absorbed by alithium bromide solution. Lithium bromide solution isbasically nothing more than salt water. However, lithi-um bromide is a salt with an especially strong attractionfor water. The mixture of lithium bromide and the re-

frigerant vapor - called the “dilute solution” - now col-lects in the bottom of the lower shell.

Generator

The dilute solution is then pumped through the heatexchanger, where it is preheated by hot concentratedsolution from the generator. The heat exchanger im-proves the efficiency of the cycle by reducing theamount of steam or hot water required to heat the dilutesolution in the generator.

The dilute solution then continues to the upper shellcontaining the Generator and Condenser, where the ab-solute pressure is approximately one-tenth that of theoutside atmosphere, or seventy millimeters of mercury.The dilute solution flows over the generator tubes andis heated by steam or hot water passing through theinterior of the tubes. The amount of heat input from thesteam or hot water is controlled by a motorized valveand is in response to the required cooling load. The hotgenerator tubes boil the dilute solution, releasing refrig-erant vapor.

Condenser

The refrigerant vapor rises to the condenser and iscondensed by the cooler tower water running throughthe condenser tubes. The liquid refrigerant flows backto the lower shell, and is once again sprayed over theevaporator. The refrigerant cycle has been completed.Now the concentrated lithium bromide solution flowsfrom the generator back to the absorber in the lowershell, ready to absorb more refrigerant. Its cycle hasalso been completed.

CONDENSER

GENERATOR

CONDENSER

WATER

STEAMCONTROL

VALVE

STEAM

CONDENSATEUNITCONTROLPANEL

CH

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D L

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EVAPORATOR

AU

TO

MAT

IC D

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STA

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AT

ION

PIP

E

STABILIZER CONTROL VALVE

ABSORBER

UNLOADERCONTROL VALVE C

ON

DE

NS

ER

WAT

ER

SOLUTIONHEAT EXCHANGER

EDUCTOR

SOLUTIONPUMP

REFRIGERANTPUMP

KEYCONCENTRATEDSOLUTION (LI.BR.)

DILUTE SOLUTION(LI.BR.)

INTERMEDIATESOLUTION (LI. BR.)

REFRIGERANT(WATER)

STEAM

CONDENSER WATER

CHILLED LIQUID

TO

WE

R W

AT

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CR

OS

SO

VE

R L

INE

OR

IFIC

E

ORIFICE

OR

IFIC

E

(3 SOL)

ORIFICE

ORIFICE

(2SOL)

YORK INTERNATIONAL8

MODEL YIA STANDARD STEAM CYCLE DIAGRAM

FIG. 1 – BASIC CYCLE DIAGRAM

LD04763Note: Some orifices may differ between various models.

FORM 155.16-OM1

9YORK INTERNATIONAL

The YORK IsoFlow Absorption Chillers consist of thefollowing major components and sub-systems:

Generator-Condenser Shell Assembly

This is the upper of two cylindrical shells, and it con-tains two tube bundles - the generator and the condens-er. The generator is a single pass flooded tube bundlewhen operated with steam, and may be a one or two-pass flooded tube bundle when operated with hot water.

The steam or hot water flowing through the tube bun-dle boils the water vapor from the solution that sur-rounds the outside surface of the generator tubes. Thecondenser section of this shell assembly consists of asingle-pass tube bundle through which cooling water iscirculated (condensing the water vapor boiled off in thegenerator) and a condenser pan to collect the water.

Evaporator-Absorber Shell Assembly

This is the lower shell assembly and it also containstwo sections - the evaporator and the absorber.

The evaporator consists of a single or multi-pass tubebundle, a refrigerant pan, and a refrigerant spray head-er assembly. The liquid to be chilled (usually water)flows through the tubes to be cooled by vaporization ofthe liquid refrigerant (water condensed in the condens-er). The liquid refrigerant is pumped through the spraysand flows down over the outside surface of the evapo-rator tubes.

The absorber consists of a single or multi-pass tubebundle, the absorber spray header assembly, and thelower part of the shell, which serves as a solution stor-age pan. Tower water is circulated through the absorbertubes to cool the lithium bromide solution beingsprayed over the outside of the tubes. This aids theabsorption process.

Solution Pump

The unit has one solution pump mounted under thelower shell. This pump transfers dilute solution to thegenerator from the absorber and, with the aid of aneductor, pumps mixed (intermediate) solution to theabsorber sprays.

Refrigerant Pump

All units have one refrigerant pump mounted beneaththe lower shell to recirculate refrigerant to the evapora-tor sprays and over the evaporator tubes.

Heat Exchanger

The heat exchanger is mounted under the lower shell toimprove system efficiency by transferring heat fromthe warm concentrated solution (low water content) tothe relatively cool dilute solution (high water content)on its way to the generator. This assists both the gener-ator in heating and the absorber in cooling the diluteand concentrated solutions respectively.

Purge System

YORK absorption systems are designed and manu-factured for extreme leak tightness to ensure againstinfiltration of non-condensables into the high-vacuumsystem. Leakage of air into the system will deterioratethe refrigeration capability of the unit as the absolutepressure in the unit rises, and corrosion problemscould develop.

The purge system provides a means for ridding the unitof any such accumulation of non-condensables. Thesystem consists of a purge header arrangement in thebottom absorber section, a purge drum, a purge pump,and associated connection piping with hand valves.During unit operation, condenser water is circulatedthrough a coil in the purge drum while solution issprayed over the coil, inducing and absorbing watervapor and making it possible to pump a higher concen-tration of non-condensables (if they exist) from thesystem by means of the purge pump furnished with thesystem.

Controls and Wiring

An electronic control system is provided with eachabsorption unit to permit automatic or manual controlof the system. Provisions are made for the following:

1. Automatic capacity control involving electroniccontrols for steam or hot water valves.

2. Safety controls involving flow switches, floatswitches, low refrigerant temperature cut-out, mo-tor overloads and protective thermostats.

3. Special control features to provide for steam econ-omy and for prevention of crystallization.

DESCRIPTION OF MAJOR COMPONENTS AND SUB-SYSTEMS

YORK INTERNATIONAL10

units and 50 HZ, 380 volts units.

2CB – Circuit Breaker

Takes the place of 3FU on 60 Hz NEMA 4 units and 50Hz, 380 volts units.

1M – Starter/Contactor for Solution Pump

Used on all units.

2M – Starter/Contactor for Refrigerant Pump

Used on all units.

3M – Starter/Contactor for Purge Pump

Used on all units.

1OL thru 3OL – Overloads

Each starter/contactor is accompanied by a heater ele-ment overload with resetting capability. The designa-tion number of the overload matches the designationnumber of the starter/contactor.

MTH1 and MTH2 – Motor Thermostats

Used on all units with Buffalo Pumps. These Klixontype thermostats are imbedded in the motor windingsand will open when the motor internal temperaturereaches 300°F (150°C) to 392°F (200°C), dependingon pump type. The thermostats will automaticallyreset when the motor windings cool down 27°F (15°C)from the trip point.

4. Functional controls which permit operation over awide range of condenser water temperatures.

COMPONENTS IN THE CONTROL CENTER

See IsoFlow Panel Instruction, Form 155.16-O3.

COMPONENTS IN POWER PANEL (See Figure 2)

1SW – Service Disconnect Switch

This is a non-fused, service disconnect switch. Theincoming power lines from the customer-suppliedfused disconnect switch or circuit breaker should beconnected to terminals L1, L2, and L3 of this switch.

1T – Transformer

This is a step-down transformer that reduces the unit'sincoming power (primary) down to the required controlvoltage of 120/115-1-50/60 (secondary).

1FU, 2FU, 3FU – Control Fuses

Used on all 60 Hz standard (NEMA 1) units. 1FU and2FU are on the primary side of the 1T transformer. Theamperage rating of these fuses depends on the unit'svoltage. The 3FU fuse is always a 10-amp fuse and ison one leg of the secondary coil of the 1T transformer.It is used for the control panel voltage.

1CB – Circuit Breaker

Takes the place of 1FU and 2FU on 60 Hz NEMA 4

CONTROL DESCRIPTIONS

FORM 155.16-OM1

11YORK INTERNATIONAL

FIG. 2 – TYPICAL POWER PANEL (60 HZ, NEMA 1 STANDARD UNIT POWER PANEL SHOWN)

26897A

POWER TRANSFORMER 3OLSERVICE

DISCONNECT SWITCH

1FU

1OL

2FU

3FU

2OL

1M 2M 3M TB2 GROUND


CONTROL COMPONENTS EXTERNAL TO THECONTROL CENTER (See Figure 3)

Hermetic Motor Thermostats (Not Shown) –

The Buffalo Solution and Refrigerant pump motorsare cooled by the circulating fluid. In the case of inad-equate cooling, each motor has an internal motor pro-tector of the Klixon type imbedded in the motor wind-ings to protect the motor from damage if overheatingoccurs.

1F – Refrigerant Level Float Switch

This float switch is installed in a separate chamber onthe side of the refrigerant outlet box, hanging off theevaporator. It senses when the refrigerant level is lowenough that the refrigerant pump could cavitate andcease to sustain the flow of refrigerant to the evapora-tor sprays. Should this occur, as it will at low loadswith low tower water temperature to the absorber,3SOL will be energized to permit solution to comeinto the refrigerant circuit to satisfy the pump needsand sustain unit operation.

3F – Refrigerant Pump Cutout Float Switch

This float switch is installed in a separate chamberlocated on the refrigerant pump suction line just up-stream of the refrigerant pump inlet. It is used in con-junction with 1F to detect insufficient refrigerant tothe Buffalo refrigerant pump. When the refrigerantlevel has decreased below the level that allows refrig-erant pump cutout float 3F switch to open and itremains open continuously for the duration of the pro-grammed preset time, the refrigerant pump will beshut down.

FLS – Flow Switch (Chilled Water)(Not Shown) –

The purpose of this switch is to stop the unit wheninsufficient chilled water is flowing to provide satis-factory operation. The switch is customer-installed ineither the chilled inlet or outlet line and wired to thecontrol panel. For instructions on how to install thisswitch, refer to Form 155.16-N3, “IsoFlowInstallation Manual”.

1SOL – Motor Coolant Solenoid Valve

Not used on units with Buffalo Pumps.

2SOL – Stabilizer Refrigerant Solenoid Valve

Basically, the 2SOL works in conjunction with theAutomatic Decrystallization mode of the unit. WhenRT2 senses an increase of temperature to 160°F(71.1°C) in the ADC line, the stabilizer refrigerantsolenoid valve is energized for 2 minutes. This trans-fers refrigerant to the generator's drain line and thusto the shell side of the heat exchanger to dilute thesolution.

A second function of this solenoid valve is to manu-ally energize it from the micro control panel to act asa refrigerant "blow down". For further details of thisvalve and its operations, refer to Form 155.16-O3,“Operators Manual – Control Panel”.

3SOL – Refrigerant Level Solenoid Valve(Unloader Valve)

The function of this valve is two-fold: 1. It transfersdiluted solution from the discharge of the solutionpump to the evaporator refrigerant outlet box. Whenfloat 1F opens, 3SOL energizes to allow solution toflow, thus keeping the refrigerant pump from cavitat-ing. This might occur at light loads and with low tem-perature tower water to the absorber shell. 2. Whenthe solution is allowed to mix with the refrigerant, thecontamination decreases the refrigeration effectthrough the evaporator, thus allowing the unit to stayonline longer during periods of low loads.

4SOL – Automatic Shut-Off Valve (Not Shown)

This valve is a customer supplied and installed valve.It is located upstream of the YORK-supplied controlvalve. It ensures 100% shut-off during a cycling/safe-ty shutdown or a power failure. It works in conjunc-tion with the 6SOL steam condensate drain solenoidvalve. For details on this valve, refer to Form 155.16-N3, “IsoFlow Installation Manual”.

5SOL – Purge Solenoid Valve

This valve is no longer used with units that haveWelsh vacuum pumps installed from the factory.

6SOL – Steam Condensate Drain Solenoid Valve(Steam units only) (Not Shown)

This valve is located on the condensate outlet box ofthe generator shell, opposite the steam inlet. It is a

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AB

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VIE

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CONDENSERBUNDLE

POWERPANEL

OIL TRAP

ABSORBERBUNDLE

ABSORBERSIGHT GLASS

REFRIGERANTLEVELSOLENOID (3 SOL)

SERVICEVALVE

SOLUTION LINETO ABSORBERSPRAYS

SOLUTIONPUMP

RERIGERANTPUMP CUTOUTFLOAT SWITCH(3F)

REFRIGERANTOUTLET BOX REFRIGERANT

LEVEL FLOATCHAMBER (1F)

REFRIGERANTPUMP AUTOMATIC

DECRYSTALLIZATION PIPE

SOLUTION RETURNLINE FROMGENERATOR

REFRIGERANTCONDENSATELINE TOEVAPORATOR

GENERATOROUTLET BOX

CONTROLPANEL

REFRIGERANTLINE TOEVAPORATORSPRAYS

INITIALPURGEVALVE

PURGE DRUM

HIGH-TEMPERATURECUTOUT SWITCH (HT1)

SOLUTION SUPPLYLINE TO GENERATOR

REFRIGERANTANTI-FREEZE LINE

00101VIP

EVAPORATORBUNDLE

GENERATORBUNDLE

RUPTUREDISK

PURGEPUMP

PURGE VALVE

normally closed (NC) valve and is energized at alltimes during unit operation. The function of this valveis to stop all steam flow through the generator whenthe unit is off or during a power failure. This valve isshipped loose with the unit for field installation. SeeForm 155.16-N3, “IsoFlow Installation Manual” fordetails on installing this valve.

HP1 – High Pressure Cutout Switch (Not Shown)

This digital safety switch is located directly off thetop of the condenser shell, control panel side, and ishardwired directly into the control panel. It is factorypreset to trip the unit when the unit internal pressurereaches 710 mm Hg Abs. It will automatically resetitself when the units pressure reduces to 40 mm HgAbs.

HT1 – High Temperature Cutout Switch

This digital safety switch is located on the controlpanel side of the generator shell with an accompany-ing thermistor inserted into an adjacent thermowell. Itis hardwired directly into the control panel and facto-ry set to trip the unit when the generator shell skintemperature reaches 330°F (165.6°C). It has a manu-al reset push button and an amber light on the controlto indicate it is functioning.

LRT – Low Refrigerant Temperature CutoutSwitch

This digital safety switch is located on the oppositeside of the refrigerant outlet box from the 1F float

14

switch. It has an attached thermistor, which is insert-ed into a thermowell that is located on the refrigerantline leading out of the bottom of the refrigerant outletbox. The switch protects the unit from freezing refrig-erant. It is factory preset to trip at 39.1°F (3.9°C). Itwill automatically reset when the temperature differ-ence increases 5°F (2.78°C).

Control Valve (Not Shown)

This valve is used to control the amount of heat ener-gy (steam or hot water) that enters the generator sec-tion of the unit.

It receives a control signal (115VAC) from theControl Panel to open or close to control the LeavingChilled Water Temperature (LCWT) to the LeavingChilled Water Temperature Setpoint. If the heatsource is steam, the maximum inlet temperature is337°F (169°C). If the heat source is hot water, themaximum inlet temperature is 266°F (130°C).

CONTROL SEQUENCE

For Control Sequence, see Form 155.16-O3,“Operators Manual – Control Panel”.

YORK INTERNATIONAL

FORM 155.16-OM1


SYSTEM CONTROL COMPONENT LOCATIONS

LD05990

FIG. 4 – SYSTEM CONTROL COMPONENT LOCATIONS

Generator tubes are submerged in lithium bromide so-lution which enters the generator in a dilute conditionat one end and leaves concentrated at the opposite end.A portion of the refrigerant is vaporized by steam or hotwater flowing through the generator tubes, thus con-centrating the solution. (See Figure 8.)

GENERAL

(Based On Standard Steam Units – Model YIA)

The cycle diagram for Model YIA steam / hot water operated systems is shown in Figure 10. The followingdiscussion will describe the absorption system operation generally, in reference to this particular configuration.

Liquid, usually water, for air conditioning duty or pro-cess duty is chilled as it passes through the evaporatortubes by giving up heat to refrigerant flowing over theoutside of the tubes. This heat causes refrigerant toevaporate since it is at a pressure with a correspondingboiling temperature lower than the leaving chilledwater temperature. For example, water is chilled from54°F to 44°F with the evaporator at 6.3 mm. Hg.absolute pressure corresponding to 40°F boiling point.(Refer to Figure 5.)

CH

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D L

IQU

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Refrigerant vapor in the evaporator is attracted andabsorbed by intermediate lithium bromide solutionflowing over the outside of the absorber tubes thusdiluting the solution. Heat generated in the process(heat of absorption) is removed by condensing waterfrom a cooling tower or other source flowing throughthe absorber tubes. (See Figure 6.)

SYSTEM OPERATION

FIG. 5 – EVAPORATOR

LD05991

Relatively dilute solution from the bottom of the ab-sorber is pumped by the solution pump, through theheat exchanger, where it is regeneratively heated by hotconcentrated solution draining from the generator. Thesolution then travels up to the generator. (See Figure 7.)

ABSORBER

FIG. 6 – ABSORBER

LD05992

ABSORBER


EDUCTOR

SOLUTIONPUMP

ORIFICE

FIG. 7 – SOLUTION PUMP

LD05993

FIG. 8 – GENERATOR

LD05994

GENERATOR

STEAMCONTROL

VALVE

AM

CONDENSATE

FORM 155.16-OM1

YORK INTERNATIONAL 17

Concentrated solution flows by gravity and pressuredifferential through the heat exchanger, where it iscooled regeneratively by cooler dilute solution. Theheat exchanger has thus improved the efficiency of thesystem by reducing the amount of steam or hot waterrequired to heat the dilute solution in the generator andthe amount of concentrated solution cooling required inthe absorber.

An intermediate solution consisting of a mixture ofcooled concentrated solution together with dilute solu-tion from the bottom of the absorber is recirculatedover the absorber tubes by the solution pump, with theaid of the eductor, to complete the solution cycle.

Refrigerant vapor released from the dilute solution inthe generator is condensed on the condenser tubes bygiving up its heat of condensation to condensing waterpassing through the tubes. This condensing water is thesame water that has been previously used to cool theabsorber. (See Figure 9.)

CONDENSER

G

COOLING

WATER

FIG. 9 – CONDENSER

LD05995

Condensed refrigerant flows by gravity and pressuredifferential through an orifice or expansion device tothe evaporator. This refrigerant, plus that recirculatedby the refrigerant pump, is distributed over the evapo-rator tubes to complete the refrigerant cycle.

Capacity of the unit is automatically controlled fromthe temperature of the chilled water leaving the evapo-rator. The steam or hot water control valve meters thesteam or hot water flow to the generator. Refer toFigure 10 on page 18 for complete cycle diagram.


CONDENSER CONDENSER

WATER

ITONTROL

CH

ILLE

D L

IQU

ID

ABSORBER

REFRIGERANT LEVELVALVE (UNIT UNLOAD)

CO

ND

EN

SE

R W

AT

ER


EDUCTOR

SOLUTIONPUMP

REFRIGERANTPUMP

* Mild Solution at Low Loads & Low Condensing Water Temperatures except where shaded.

3SO

RT2

RT8

STEAM

MAINAIR




REFRIGERANT(WATER)

STEAM

CONDENSERWATER

CHILLED LIQUID

RT3

*

FIG. 10 – CYCLE DIAGRAM (HOT WATER UNITS & STEAM UNITS)

LD04764Note: Orifices may differ between various models.

FORM 155.16-OM1


CONDENSING WATER % NOMINALINLET TEMPERATURE UNIT TONS

45°F (7.2°C) 4355°F (12.8°C) 5865°F (18.3°C) 7874°F (23.3°C) 100

General

The YIA control panel operates to control the capacityof the system by the throttling action of the steamvalve.

Maximum Load Limits at Reduced CondensingWater Temperatures

All York IsoFlow absorption units which incorporatethe Millennium Control Center have a programmableentering condenser water temperature from 75°F to125°F (23.8°C to 51.6°C). The programmed value isbypassed for the first 30 minutes at unit start-up. Formore details on how to program and operate theMillennium Control Center see Form 155.16-O3,“Operators Manual – Control Panel”.

For all model units, the minimum entering condensingwater temperature for full load operation is 74°F(23.3°C). The chart below is an approximation of per-cent of full load tonnage achievable for different con-densing water inlet temperatures:

Because of load variations, outside wet bulb tempera-tures, and cooling tower size, the refrigeration loadmay tend to exceed the maximum allowable. In thiscase, the tower fan thermostat(s) must be set to adjusttower capacity as required. Fan cycling or speed modi-fication is thus used to produce any desired minimumcooling water temperature. For maximum economyand stability of operation, the tower fan thermostat(s)should be set to give the lowest cooling water temper-ature possible without the temperature cycling belowthese limits.

As the condensing tower water temperature reduces,hence a reduction in the water temperature to theabsorber/condenser bundles, increased activity in thegenerator occurs. This causes carry-over of solutionfrom the generator bundle to the condenser bundle toan undesirable degree.

CAPACITY CONTROL

0 10 20 30 40 50 60 70 80 90 100

65

60

55

50

45

40

A – Max. Tonnage Limit

AVERAGE

55˚F (12.7˚C)A

VE

RA

GE

SO

LUT

ION

CO

NC

EN

TR

ATIO

N IN

SO

LUT

ION

CIR

CU

IT (

%)

75˚F (23.8˚C)

45˚F (7.2˚C)

65˚F (18.3˚C)

85˚F (29.4˚C)

AVERAGE

PERCENT LOAD

FIG. 11 – ISOFLOW ABSORPTION SYSTEM SOLUTION CONCENTRATION, AVERAGE IN SYSTEM SOLUTIONCIRCUIT

LD04765

On the chart below, these limits are indicated by linesB and C for their corresponding ranges. The chartassumes that the unit is free of scale and non-condens-ables.

Solution and Refrigerant Interchange During Operation

The absorption system accommodates varying loadsand cooling water temperatures by varying the solutionconcentration in accordance with the representativeconcentration chart, Figure 11. The IsoFlow units carrysufficient reserve refrigerant (water) within the systemto permit the load to drop to approximately 10% at afixed cooling water temperature above about 75°F.Figure 11 indicates that the average solution concentra-tion within the system would be approximately 50-51%for operation at these higher fixed cooling water tem-peratures.

1. Solution and refrigerant variation with loadvariation at higher cooling water temperatures -Table 1 illustrates, in a rough way, variation ofrefrigerant quantity in the refrigerant circuit, and

(COOLING WATER TEMP)


FIG. 12 – SOLUTION AND REFRIGERANT LEVELVARIATION WITH LOAD

a reduction in water content as shown in Item 5. At100% capacity, only 129 pounds of water wouldstill exist in the drum of solution as charged intothe system. Item 6 shows that the total weight ofsolution would then be 341 pounds, for each drumcharged into the system, and that 59 pounds ofwater would have been driven off.

Figure 12 shows in a rough way what happens torefrigerant and solution levels as the system ca-pacity changes. The top view shows the levels inthe lower shell at 25% load. Much of the water isback in the solution, so the solution level is cor-respondingly high in the bottom of the shell. Therefrigerant level in the refrigerant drain pan,however, is relatively low. On the bottom view,also showing the lower shell, but at a 100% loadcondition, much of the refrigerant has been driv-en from the solution, and consequently the vol-ume of solution in the bottom shell is reduced. Atthe same time there is more refrigerant in therefrigerant circuit and the evaporator drain panlevel is consequently high.

LD04766

TABLE 1 – PART LOAD OPERATION –APPROXIMATE VALUES ONLY

LOAD% 25% 50% 75% 100%

Solution Concentration1 Leaving Generator 59 61 63 64.32 Leaving Absorber 54 56 58 59.33 System Average 56 58 60 62.0

Per Drum of Solution4 Lbs. 221 212 212 2125 Lbs. Water in Solution 167 154 142 1296 Total Weight In Solution 379 366 354 3417 Water Driven Off, Lbs. 21 34 46 59

Generator Operation8 Solution Temp. Leaving. Gen. 167 184 201 2109 Steam Pressure, PSIG 1 1 2 9

solution quantity in the solution circuit, as the per-cent load varies. The values shown are approxi-mate only, and are to be taken only as indicating ageneral trend rather than a guide for absolute set-tings.

In Item 2, Table 1, it is noted that concentrationleaving the absorber at 100% load is approximate-ly 59.3%. At 25% load the concentration mustdrop, and would be in the order of 54.0%. Byreducing the concentration, the capacity of theabsorber falls off and thus the absorption systemcapacity is reduced.

This of course, as explained above, is broughtabout mainly by throttling of the steam valve, sothat the concentration leaving the generator is asshown in Item 1, where the concentration dropsfrom 64.3% at peak capacity to approximately59.0% at the 25% load condition.

Item 3 shows rough average solution concentrationthroughout the entire system.

A change in concentration from an average of 64%at 100% load, to approximate value of 56% at 25%load, brings about marked changes in the quantityof solution and refrigerant in circulation. For each400 pound drum of solution charged into the systemat 53% concentration, there is correspondingly 212pounds of lithium bromide and 188 pounds ofwater charged into the system. As steam is applied,and water vapor is driven from the solution, there is

FORM 155.16-OM1


Refrigerant Overflow – An auxiliary refrigerantoverflow pan is located near the tube sheet in sucha way that it can be witnessed through the evapora-tor sight glasses.

Since the amount of refrigerant in the refrigerantcircuit is at a maximum of 100% capacity, overflowwould normally start to take place at the 100% con-dition or slightly above. This overflow and sightglass arrangement therefore provides a methodof charging the correct amount of refrigerantinto the system, provided 100% load is obtain-able. Add refrigerant to the system until theevaporator pan is at the point of overflow at this100% load. Charging to this condition has theadded advantage of providing a safety featureagainst over-concentration. Any tendency toover-concentrate, as might be the case if the absorb-er section operation is faulty (such as with air in thesystem), would be prevented to some degree byoverflow refrigerant into the solution.

Absorber Solution Level – A large sight glass isprovided near the bottom of the absorber shell toobserve the dilute solution level in the absorber. Atsteady full load conditions, the level in the absorberwill be at its lowest, since the maximum amount ofwater (removed from the solution) will be in therefrigerant circuit. Under these conditions, the levelin the sight glass should be just visible at the bot-tom of the sight glass. As the load decreases, lessrefrigerant is generated out of solution and the levelin the absorber will increase until (at very lightloads) the level in the absorber is at its maximum(near the top of the sight glass).

If there is any doubt whether the unit is operatingnormally, a solution concentration check will indi-cate whether excessively high solution concentra-tions are being encountered.

2. Solution and refrigerant variation with loadvariations at lower cooling water temperatures –IsoFlow systems are equipped with provisions toaccommodate low load operation (down to 10%)with cooling water temperature as low as 45°F.

Referring again to Figure 11, achievement of lowcapacity at low cooling water temperature involvesreduction of concentration in the solution circuit.YORK is able to achieve considerable reduction ofconcentration of solution by generous use of addi-tional refrigerant in the basic design. Thus, water isremoved from the refrigerant circuit and is added tothe solution circuit for dilution. In the IsoFlowdesign, further dilution is brought about by removal

of lithium bromide from the solution circuit, send-ing this lithium bromide under a controlled basis tothe refrigerant circuit, for unlimited capacity con-trol possibilities.

The amount of actual lithium bromide transferred iskept to a minimum by introducing this lithium bro-mide only when the refrigerant level in the refriger-ant circuit is at a minimum operational level, atwhich time float switch 1F signals 3SOL to open andtransfer solution to the refrigerant pump circuit.

During normal summer operation where at least me-dium load prevails, lithium bromide transfer to therefrigerant circuit is not required and the YIA panelprevents transfer of solution at possible low refriger-ant level at startup. The function blocks out operationof 3SOL until the chilled water temperature is with-in range of normal operation.

To provide for lithium bromide removal from therefrigerant circuit as the system proceeds from lowload, low condensing water temperatures to higherload, higher condensing water temperatures, the sys-tem automatically transfers the lithium bromide fromthe refrigerant circuit, using a combination of variousmeans.

1. To assist in the lithium bromide removal from therefrigerant circuit as required under increasing loadconditions, the IsoFlow design utilizes on its stan-dard unit a small amount of continuous refrigerantblowdown.

2. The action of the system stabilizer (refrigerant valve2SOL) has the effect of transferring from the refrig-erant circuit.

3. At high loads and high condensing water tempera-tures approaching design conditions, any residual inthe refrigerant circuit will be removed by a tempo-rary evaporator pan overflow, if the lithium bromidehas not previously been removed by the combinationof the continuous blowdown and action of 2SOL.

4. The refrigerant is gradually purified as refrigerantcondensate makeup is accelerated with the increasein load and cooling water temperature.

When it is desired to reduce the content of lithiumbromide in the refrigerant circuit more rapidly thanwould automatically occur, the service engineer can enter the electronic panel and energize 2SOLmanually.

It should be noted that the conditions during whichthe lithium bromide content appears high are at lowload and low cooling water temperature, at whichtime the evaporator pan is essentially empty and the

YORK INTERNATIONAL22 YORK INTERNATIONAL

Capacity Control Valve Override

Under startup conditions, and again during normaloperation with changing load or changing coolingwater temperatures, a signal may be sent to the capac-ity control valve for maximum opening, simultaneouswith a relatively low cooling water temperature. Anunnecessarily high solution concentration and exces-sive violent action in the generator can result. IsoFlowunits provide an override control, to automaticallyreduce the maximum setting of the steam valve relatedto cooling water temperature.

Automatic Decrystallization Control

The operation of units with the ADC control circuit isdescribed in detail in the section "Discussion of Sub-System Operation" below.

DISCUSSION OF SUBSYSTEM OPERATION

Automatic Decrystallization Feature

Units can crystallize when the concentration of lithiumbromide is excessive for a given temperature. Thiscould happen in the shell-side of the heat exchangerand could extend to the piping and the eductor, caus-ing stoppage of flow and producing a noisy condition.The automatic decrystallization feature is available onall IsoFlow Absorption Systems. All models areequipped with this basic ADC piping circuit plus theADC control feature.

The automatic decrystallization feature is a valuableasset in striving for trouble-free operation. While theADC piping circuit will not completely eliminate thepossibility of a condition of crystallization requiringservice assistance, it will greatly reduce the likelihood.A tendency for mild temporary crystallization whichmight occur in rather extreme condensing water tem-perature variations can be automatically taken care ofwithout loss of refrigeration or special attention fromthe operator. Still more positive measures attacking themajor factors in solution crystallization are taken inmodels where the ADC controls are utilized. Directdilution of the solution with refrigerant and reducingthe heat input to the generator when the tendency tocrystallize is automatically detected are both affectedby ADC controls, arranged to continue in effect untilthe tendency to crystallize disappears.

need for the more efficient evaporation is insignifi-cant. At higher loads and cooling water tempera-ture, the evaporator automatically becomes totallyefficient.

ANTI-FREEZE LINE

For sustained operation at low loads and low condens-ing water temperature, the concentration of lithiumbromide by weight in the refrigerant circuit mayapproach 35% - 40%. With conditions such as these,the pressures in the lower shell are reduced. The purewater refrigerant entering the evaporator from the con-denser would at these times be below the freezingpoint of water (32°F) by as much as 12%, and couldcause ice to hang up in the refrigerant condensate linesfrom the condenser after the orifices.

To prevent this, a small amount of refrigerant (actual-ly very dilute solution now in the refrigerant circuit) isrouted from the discharge of the refrigerant pump tomix with the pure water refrigerant about to enter theevaporator from the condenser. This line is identifiedon the cycle diagram Figure 10 as the antifreeze line.

Chilled Water Control Stability

Operation of an absorption system without the towerwater bypass valve control to maintain a given coolingwater temperature to a unit requires certain controlmeasures within the unit to maintain acceptable stabil-ity of operation. The effect of rapidly changing towerwater temperature, such as occurs when tower fanscycle off and on, would affect the unit capacity control,causing steam valve opening and closing tendencies tocut-out on refrigerant low temperature thermostat ifprovisions were not made to offset these tendencies.

Stabilizer Refrigerant Solenoid (2SOL)

IsoFlow units are equipped with a control stabilizer ar-rangement. This control operates the refrigerant valve(2SOL) to permit immediate transfer of refrigerant tothe generator drain line for immediate control of refrig-erant temperature, via dilution of the solution andhence, reduction of absorption and refrigeration effect.This type of action, when necessitated by influences ofcooling water temperature fluctuations, corrects thelow temperature condition, permits refrigeration effectto continue, and restrains from appreciably unloadingthe cooling tower such that an aggravated coolingwater temperature swing is avoided.

FORM 155.16-OM1


FORM 155.16-O3.1

YORK INTERNATIONAL

Basic Automatic Decrystallization Piping Circuit

Referring to Figure 13, the normal return solution flowfrom the generator is by way of return pipe (1), throughheat exchanger (2), and hence through pipe (3) to theeductor suction (4).

During normal operation, the flow of solution in returnpipe (1) is accomplished by a condition of “open-sewer” flow for a portion of the return pipe from (A) to(B). Below some point (B) a solid liquid level is estab-lished and solid liquid exists from (B) through the heatexchanger (2) and return pipe (3).

If a situation starts to develop such that solution con-centration from the generator is excessively high, solu-tion crystals will start to build on the shell side of theheat exchanger. This will restrict the flow through thenormal system of return piping above described, andthe established solution level (B) will rise in the returnpipe (1). This will continue to rise until an elevation(C) is reached. At this point, an emergency solutionreturn pipe is provided. This return pipe is item (9),with connection entering the return piping at (8). Thisreturn pipe (9), has a trapped section of pipe (10), riserportion (11), and pipe sections (12) and (13).

The heat exchanger is therefore bypassed in the opera-tional use of this emergency return system of piping.Its operation is completely automatic.

It should be noted that as crystallization proceeds, it isnot necessary for the solution to back up into the gen-erator itself to engage the use of this device. It is desir-able to bring the device into operation before an ex-treme condition of crystallization is experienced. Con-nection (8) therefore enters the normal return piping ata level appreciably below the normal generator operat-ing level (17). Since this enters the return piping at apoint where there is open sewer flow, there is no flowof solution down this emergency decrystallization pipeduring normal operation.

It is necessary that this automatic decrystallization pipecontain a liquid trap. Otherwise, there would be un-wanted flow of vapor from the top shell to the lowershell due to the difference in pressures between the twoshells.

ADC Flush Line

To provide a liquid trap, a small capacity flush line isprovided (14), to supply a small GPM flow of dilute-solution into the trapped portion of the decrystalliza-tion pipe. It is desirable that the riser portion of thistrap be sufficiently high to take care of any extremecondition in top shell pressure, such as with unusuallyhigh condensing water temperature and degree of con-denser fouling.

Consequently, a riser portion is extended up into exte-rior pipe (12). This pipe (11) inside pipe (12) is an ex-tension of pipe (10).

This flow of flush solution through the trap also servesthe purpose of sweeping out the small amount of watercondensate that tends to be absorbed into the dilute so-lution at the liquid-vapor interface.

In the operation of the unit, one can easily tell whetherthe solution flow from the generator is by normal returnmethods through the heat exchanger, or whether theautomatic decrystallization pipe is being used. By plac-ing the hand on pipe (10), or pipe (13), a hot tempera-ture such as that normally experienced at pipe (1) wouldindicate that solution is returning by means of the auto-matic decrystallization pipe. A relatively low tempera-ture, corresponding to normal temperature of dilute so-lution or slightly above, would indicate that there is noreturn flow through the automatic decrystallizationpipe.

Combination of Basic ADC Piping Circuit andADC Control Feature (See Figure 13)

The basic ADC piping circuit is installed and broughtinto play and operates the very same way in this appli-cation as described above. The additional protectionafforded by the ADC Controls feature is therefore dis-cussed here.

As hot concentrated solution backs up and overflowsinto emergency solution return line (9), the temperatureof the pipe increases and the ADC sensor item (18),attached to the pipe, senses this temperature. At a tem-perature of approximately 160°F, item (18) starts a con-trol panel timer, which signals the capacity control valve(23) to close to 50% for a minimum of 10 minutes.During the first 2 minutes, 2SOL (Item 16) is energized


ITEM NO. DESCRIPTION13 A.D.C. OVERFLOW DUMP LINE14 A.D.C. FLUSH LINE15 REFRIGERANT VALVE CONNECTION16 REFRIGERANT VALVE (2SOL)17 SOLUTION LEVEL IN GENERATOR18 A.D.C. THERMOSTAT (RT2)19 CAPACITY CONTROL VALVE

A START OF OPEN SEWER FLOWB TOP OF SOLID LIQUID LEVEL C A.D.C. SOLUTION OVERFLOW POINT

ITEM NO. DESCRIPTION1 SOLUTION RETURN PIPE2 SOLUTION HEAT EXCHANGER3 EDUCTOR SUCTION4 EDUCTOR5 SOLUTION PUMP SUCTION6 SOLUTION PUMP DISCHARGE7 GENERATOR SUPPLY LINE8 A.D.C. PIPE OVERFLOW CONNECTION9 A.D.C. PIPE10 A.D.C. PIPE (TRAPPED SECTION)11 A.D.C. PIPE (RISER SECTION)12 A.D.C. OVERFLOW JACKET

LEGEND TO FIG. 13

to permit refrigerant to be pumped into line (1) via con-nection (15). The cycle will be repeated until line (8)cools to approximately 150°F, or lower, signifying ease-ment of the crystallization condition and normal circu-lation of solution from the generator such that overflowinto line (9) has ceased.

It must be noted that the ADC operation will continuefor at least 10 minutes regardless of a shutdown or sub-sequent restart.

2SOL – Refrigerant Valve Blowdown

Manual operation of the refrigerant valve (2SOL) maybe selected by using the manual pump key in theProgram mode. When this valve is energized, refriger-ant will flow through the line, into the shell side of theheat exchanger and ultimately into the absorber shell,thus transferring refrigerant back into the solution sideof the system.

FORM 155.16-OM1

25YORK INTERNATIONALYORK INTERNATIONAL




REFRIGERANT(WATER)

STEAM

CONDENSERWATER

CHILLED LIQUID

CONDENSER CONDENSER

WATER

CH

ILL

ED

LIQ

UID

ABSORBER

REFRIGERANTLEVEL VALVE

CO

ND

EN

SE

R

WAT

ER

SOLUTIONHEATEXCHANGER

4EDUCTOR

SOLUTIONPUMP

REFRIGERANTPUMP

3SOL

STEAM

PURGEDRUM

1

C

8A

7

1

18

11

B

9

1316

66

2

10

15

3

ORIFICE

FIG. 13 – AUTOMATIC DECRYSTALLIZATION FEATURE (HOT WATER UNITS & STEAM UNITS WITH ADC CONTROL)

LD04768

Note: Orifices may differ between various models.


SECTION 3 – PURGE SYSTEM OPERATION (Refer To Figure 15)

PurgePump

Water

Leak Rate Test Valve (close for test)

Gas Ballast Valve (close for test)

OilDrainValve

OilTrap

LD06050

FIG. 14 – BUBBLE TESTING FOR LEAKS

Each system is equipped with a purge pump forremoving any air and other noncondensable gasesfrom the system. A minimum purging sequence ofonce per week is recommended.

Do not operate purge pump untilpump has been properly chargedwith DUOSEAL Purge Pump Oil.

Do not operate purge pump duringwarming or cooling operations tocorrect a severely crystallized unit.

The purge system is operated as follows:

1. Start the Purge pump through the control panel.Run the pump for 10 minutes with the gas ballastvalve open and check the vacuum on the gauge. Itmust be 2mm Hg or less.

2. Establish the leakage rate of the purge pump andthe unit using the bubble test procedure, Fig. 14.

a. Purge Pump - After reading the 1-2mmHg ofmercury vacuum that the pump is capable ofattaining, close the ballast valve and the leakrate test valve. Place the hose from the dis-charge of the pump into a small container ofwater. Insert the tube approximately 1/4" in thewater. Wait about 5 minutes to allow all residu-al air in the pump to be removed. Then countthe number of bubbles leaving the hose in 1minute. There should be no more than 1 to 2bubbles.

b. Unit - Without changing the position of the bal-last valve, open the manual purge valve to theunit. Wait about 5 minutes before reading theunit bubble rate. Usually a quantity of non-con-densables have accumulated in the purge drumprior to opening the unit valve. This allowsthem to be removed so you can obtain a moretrue reading of any leakage that exists in theunit.

Then open the ballast valve on the purge pumpand purge unit for approximately 30 minutes.Close the manual purge valve on the unit andlet the purge pump run for 30 minutes. Thiswill help to remove any condensation thatbecame entrained in the oil, cleaning it up. Ifthis clean-up period is not followed, the oil willhave to be changed more often to maintainpump efficiency.

3. To verify the effects of the purging performed onthe unit:

a. After clean-up sequence, close the ballast valveand proceed as mentioned in 2a. The purgepump rate should have returned to the same ratefor the pump that you recorded earlier. If not, an oil change or more clean up time may be required.

b. If so, then open the unit manual hand valve.After waiting 5 minutes, read the unit bubblerate again. Bubble rate change from 2b to 3bequals the effect of purging.

c. Close the unit manual hand valve, remove dis-charge hose from container, and open the ballastvalve. Stop vacuum pump via the control panel.

d. Repeat purging operation at each start up.Check unit bubble rate periodically to deter-mine required frequency of purging. If exces-sive purging is required, the unit must be shutdown. Contact the nearest YORK FieldRepresentative.

e. If the purge pump fails to produce the desiredvacuum, refer to the Purge Pump Maintenancesection for details.

FUNCTION

Since this type of chiller operates at very low levels ofvacuum, if there is the slightest leak in the pipingsome non-condensables will infiltrate the system.When this happens, there is a purging system in placefor removing these non-condensable materials.

FORM 155.16-OM1


COOLING WATER FROMCONDENSER WATER BOX COOLING WATER TO

CONDENSER WATER BOX

PURGE DRUM

NON-CONDENSABLESTO PURGE PUMP

UNIT HAND VALVE(Open ONLY When Purging From Unit)

DILUTE SOLUTION FROMDISCHARGE LINE OF

SOLUTION PUMP

COOLING COIL

VAPOR RELIEF LINEINTO EVAPORATOR

UNIT INITIALCOMISSIONING

HAND VALVE

INTO SIDE OF ABS./EVAP.

SHELL

U-TUBEISOLATION

HAND VALVE

U-TUBEMANOMETER

GAS SAMPLE FROMABSORBER SHELL HEADER

SOLUTION RETURNTO ABSORBER BELLY

AUX. CONNECTION

OILTRAP

CHECK VALVE

SUCTIONHOSE

PUMPDISCHARGE

LEAK RATETEST VALVE

BUBBLETEST HOSE

OIL DRAIN

PURGEPUMP

MOTOR

GAS BALLAST VALVE

FIG. 15 – ISOFLOW PURGE SYSTEM

LD05998


COOLING WATERFROM CONDENSERCIRCUIT

NON-CONDENSABLESTO PURGING SYSTEM

GAS SAMPLEFROM ABSORBER

SOLUTION RETURNTO ABSORBER

DILUTE SOLUTIONFROM DISCHARGELINE OF SOLUTION

PUMP

.........

LD06026

FIG. 16 – PURGE DRUM DETAILS

PURGEDRUM

HAND VALVE

OPEN ONLYWHEN PURGINGFROM UNIT

CONDENSERWATER CONNECTIONSFOR THE COOLING COIL

RELIEF LINESINTO EVAPORATOR

OPEN ONLY ON INITIAL START-UPTO PURGE FROM UPPER PORTIONOF ABSORBER SHELL AND EVAPORATOR

DILUTESOLUTIONFROM DISCHARGELINE OF SOLUTION PUMP

GAS SAMPLEFROM ABSORBERPURGE HEADER

SOLUTION RETURNTO ABSORBER

MOTOR PUMP

FOR EXTERNALVACUUM PUMP

OILTRAP

DISCHARGE

U-TUBEVALVE

U-TUBEMANOMETER

VAPOR RELIEF LINE INTO EVAPORATOR

FIG. 17 – THE COMPLETE PURGE SYSTEM

LD06027

The most common non-condensables found in thepurge exhaust of an absorption-type chiller are as fol-lows: nitrogen (N2), anhydrous ammonia (NH3),nitrous oxide (N2O), nitrogen dioxide (NO2), nitrogentetroxide (N2O4), various other compounds of nitro-gen, and hydrogen gas (H2). Keep in mind that onIsoFlowTM chillers with chromate inhibitor, none ofthese gases will be present.

SYSTEM DETAILS

The system consists of a suction probe arrangement inthe Purge Drum, spray header, cooling coil, and a vac-uum pump, along with interconnecting piping.

In the Purge Drum, condenser water is circulatedthrough a coil, thus inducing and absorbing watervapor and making it possible to pump a higher con-centration of non-condensables from the system bymeans of the Purge Pump. Details of the innards ofthis Purge Drum can be seen in Fig. 16.

The Presence and Removal of Condensate -Condensation takes place particularly in the compres-sion stroke of the second stage of a two-stage pump.The compression stroke is that portion of the cycleduring which the gas drawn from the intake port iscompressed to the pressure necessary to expel it pastthe exhaust valve. Condensation takes place when theratio between the initial pressure and the end pressureof the compression is high, that is, when the mixtureof vapor and gas drawn from the intake port is com-pressed from a low pressure to a high pressure. Byadding air through the gas ballast valve to the mixtureof vapor and gas being compressed, the pressurerequired for delivery past the exhaust valve is reachedwith a considerably smaller reduction of volume ofthe mixture; thus, depending upon the amount of airadded, condensation of the vapor is either entirelyavoided or substantially reduced.

OIL LEVEL DETERMINATION

The amount of oil suitable for efficient and satisfacto-ry performance should be determined after the pumphas reached its operating temperature. Initially, how-ever, the pump should be filled with fresh oil whilethe pump is idle. Fill the pump through the pump dis-charge port until the oil level falls halfway up the oillevel window. If after a short period of operation, thelevel should fall, it is likely the result of oil enteringsome of the interior pockets of the pump. If the oillevel rises, this signifies oil had drained into the pumpcavity while idle. Shut off pump, then drain oil downto proper level.

GENERAL

As previously discussed, each machine is equippedwith a vacuum pump (refer to Fig. 19, for pump spec-ifications) which is designed to remove non-condens-ables from various areas of the machine. The follow-ing issues should be kept in mind whenever operatinga YORK Vacuum Pump.

Cleanliness

Take every precaution to prevent foreign particlesfrom entering the pump. A fine mesh screen is pro-vided for this purpose in the intake passage of allYORK Vacuum Pumps.

Types of Lubricants

All YORK mechanical vacuum pumps are tested withDUOSEAL® oil and shipped with a full charge to pre-vent unnecessary contamination. DUOSEAL® oil hasbeen especially prepared and is ideally suited for usein mechanical vacuum pumps because of its desirableviscosity, low vapor pressure and chemical stability.

The vacuum guarantee on all YORK vacuum pumpsapplies only when DUOSEAL® oil is used.

PURGE PUMP PIPING AND OPERATING VALVES

The purge pump piping and valves, illustrated inFigure 15, is installed at the factory and can be usedfor several functions. During normal operation, boththe gas ballast and the leak rate test valve must beopen at all times.

The Principle of Gas Ballast

The Effects of Unwanted Vapor - Systems whichcontain undesirable vapors cause difficulty from boththe standpoint of attaining desirable ultimate pres-sures, as well as contamination of the lubricatingmedium. A vapor is defined as the gaseous form ofany substance which is usually a liquid or a solid.Refrigerant (water) and alcohol vapors are two of themost common vapors encountered in absorptionchillers. When such vapors exist in a system, thevapors or mixtures of gas and vapor are subject tocondensation within the pump. This precipitated liq-uid may dissolve or become emulsified with the oil.This emulsion is recirculated to the chambers of thepump where it is again volatized, causing increasedpressure within the system.

FORM 155.16-OM1


SECTION 4 – PURGE PUMP OPERATION

PurgePump

Leak Rate Test Valve (Open)

Gas Ballast Valve (Open)

BubbleTest Hose

Oil Drain

OilTrap

FIG. 18 – PURGE PUMP PIPING AND VALVES - NORMAL OPERATION

LD06051


If a gurgling sound occurs, additional oil may need tobe added. Mechanical pumps will gurgle in varyingdegrees under four conditions of performance: (1)when operating at high pressure as in the beginningcycles of evacuation of the purge drum; (2) when theoil level in the pump reservoir is lower than required;

(3) when a large leak is present in the system; and (4)when the gas ballast is open. Best performance of amechanical pump is generally obtained after suffi-cient time has been allowed for the pump to come tooperating temperature.

SECTION 5 – PURGE PUMP MAINTENANCE

VACUUM PROBLEMS

Pressure Determinations

A simple test for the condition of a mechanical pumpis a determination of its ultimate pressure capability.This can be accomplished by attaching a gauge direct-ly to the pump. The gauge may be any suitable typeprovided consideration is given to the limitations ofthe gauge being used. The pump must be capable ofpulling a vacuum of at least 2 mmHg Abs. If the pres-sure is unusually high, the pump may be badly con-taminated, low on oil or malfunctioning. On the otherhand, if the pressure is only slightly higher than theguaranteed pressure of the pump, an oil change maybe all that is required.

Oil Contamination

The most common cause of a loss in efficiency in amechanical pump is contamination of oil. It is causedby condensation of water and alcohol vapors and byforeign particles. The undesirable condensate emulsi-fies with the oil which is recirculated and subjected tore-evaporation during the normal cycle of pumpactivity, thus reducing the ultimate vacuum attainable.Some foreign particles and vapors may form sludgeswith the oil, impair sealing and lubrication and causeeventual seizure. Although the gas ballast valve ishelpful in removing vapors, especially water, it is notequally effective on all foreign substances; therefore,periodic oil changes are necessary to maintain effi-cient operation. The required frequency of changeswill vary with the particular system.

The oil should be changed when it looks dirty, cloudy,milky, or when the pump is not capable of pullingbelow 2mmHg Abs.

OIL CHANGES AND OIL LEVEL

Draining the Pump

An oil change is most easily accomplished when thepump is warm and the oil is less viscous. Use a con-tainer large enough for the oil in the particular pump.Stop the pump, and open the drain valve. A thoroughjob may be accomplished by tipping the pump slight-ly, if this is possible. The small residue remaining inthe pump may be forced out by hand-rotating thepump pulley with the exhaust port partially closedand the intake port open. Closing the exhaust portcompletely under these conditions will create exces-sive pressure at the drain valve which may cause theoil being drained to splatter.

Flushing the Pump

This procedure should be performed whenever theperformance of the pump is poor and simply changingthe oil didn’t correct this shortcoming.

1. Check the oil level.

a. If the oil level is well above the fill mark, thiscan indicate the pump has ingested lithium-bromide solution. Go to step 2.

b. If the oil level is even with the fill mark and you do NOT suspect lithium bromide solu-tion has been ingested accidentally by thepump, run the pump for 15 minutes and allow the pump oil to warm up before going to step 2.

2. Turn off the motor for the vacuum pump. Drainthe oil into a clear plastic container. Look forwater settling to the bottom of the container. Insome cases, an emulsion of oil and water can beseen between the oil and the water. If water isnoticed, perform steps 3 through 5 several timesuntil the oil comes out clear.

The oil drained from the pump isfrom the oil case only. There may bewater or other contaminants in thepumping mechanism. To be sure allcontaminants have been removed,the pump mechanism needs to beflushed.

3. Make sure the belt guard is installed before pro-ceeding further. Attach a short hose to the drainvalve which runs into a clear plastic container.Secure the hose end in the container so that it doesnot blow around during the next step.

4. Flushing the pump is carried out by adding a cupof new DUOSEAL® oil through the intake (IN)port while the pump is turned on for 15-20 sec-onds. While adding the pump oil, the exhaust(OUT) port is blocked by the palm of your hand.Look for water coming out of the drain hose.Turn off the pump.

5. Repeat step 4 until only clean oil comes out of thedrain hose.

6. Fill the pump (through the exhaust port) with 2.25quarts of DUOSEAL™ vacuum pump oil.

7. Plug the intake (IN) port with a rubber stopper.Turn the pump on and run the pump for 10 min-utes. Close the gas ballast valve.

8. Check the vacuum reading of the pump by con-necting a thermocouple or pirani gauge tube to thepump’s intake. If the pump is running close tonew, the total pressure reading should be at least10 micron.

A simple way to connect the gauge tube to thepump is to run the threaded tip of the tube througha hole in the rubber stopper. Use pump oil as alubricant for inserting the tube. The stopper cho-sen should be bigger than the outer diameter ofthe intake fitting.

Refilling the Pump

Refill the pump by pouring new DUOSEAL® oil intothe exhaust port. Fill to the indicated level and startthe pump with the intake closed. A gurgling noise ischaracteristic when high pressure air is drawn throughthe pump. It should disappear quickly as the pressurewithin the pump is reduced. If gurgling continues(with gas ballast closed), add sufficient additional oilthrough the exhaust port until gurgling ceases.

FORM 155.16-OM1

YORK INTERNATIONAL 31

SHAFT SEAL REPLACEMENT

To replace the shaft seal of a pump, drain the oil andremove the pump pulley and key. Remove the screwssecuring the old seal and pry it loose with a screw-driver or similar wedge, being careful not to mar thesurface of the pump body against which the seal fits.Discard the seal and its gasket, inspect all surfacesand repair any damages with a fine abrasive stone.Wipe all sealing areas clean and place a film ofDUOSEAL® oil on both the shaft and the inside boreof the new shaft seal. Using a new gasket, carefullyslide the new seal into position and center it on theshaft. It is not necessary to apply any sealant to thegasket. Tighten the mounting screws uniformly andrefill the pump with DUOSEAL® oil. Follow instruc-tions included in repair kit.

REPAIRING OIL LEAKS

Location, Cause and Effect

Oil leaks may develop wherever two mating faces aresealed with a gasket. Such seams may fail as the resultof deterioration of the gasket material, loosening ofthe screws caused by temperature variations, orimproper care as the result of previous reassembly.Typical gasketed seams in a mechanical pump arelocated at the oil level window, the shaft seal, the oildrain and the mating faces of such mechanical sur-faces as the intake chamber cover. The importance ofa gasketed seam is determined principally by its func-tion. If it is a vacuum seal, the ultimate performanceof the pump is dependent upon it. If it is an oil seal,the pump may be operated satisfactorily for sometime without loss of function. Eventually, of course, agreat loss of oil may cause harmful damage.

Repairing Technique

An oil seam may be sealed by any of several methods.When an O-ring is employed, the surfaces of the O-ring and its groove should be wiped clean. If the O-ring is not badly deformed or scratched, it may bereused by sealing with a slight film of vacuum oil orvacuum grease. Thin composition gaskets are gener-ally used for large irregularly shaped areas. A replace-ment joint of this type should be thoroughly cleanedof all previous gasket material and the mating sur-faces cleaned of any nicks.


DRIVE PROBLEMS

When troubleshooting drive prob-lems or checking belt tension,always shut-off and lock out powerat the main disconnect switch.

If for any reason the pump will not operate, turn offand lock out the power at the main circuit breaker ordisconnect. Check the overload assembly and electri-cal connections. Remove the guard cover followed bythe belt. Re-establish power to the pump. If the motor

operates properly try hand-rotating the pump in theproper direction with the pump intake port open. Ifboth turn freely, then replace the belt and check thebelt tension. The tension should be sufficient to drivethe pump without visible slippage. Any greater ten-sion will cause noise and possible damage to the bear-ings of both the motor and pump. Make certain thatboth pulley grooves are clean and free from oil. Thepulleys must be fastened securely on their respectiveshafts, and in parallel alignment. Re-install the beltguard and check for proper operation and amperage.

Replace or re-build any defective components.

FORM 155.16-OM1


GAS BALLAST PORT,1/4" NPT FEMALE CONNECTION

3-13/16"

6"

3"

11-1/2"

41-2111 BASE

3"

5-5/16"

9-1/2"

10-1/4"

11"

19-1/4"

17-3/4"

5-1/2"

5-5/16"

11-1/16"

15-5/8"

3/4 - 20 THREAD

INTAKE NIPPLE, ACCEPTS5/8" TO 3/4" ID HOSE

1-13/16"

2-01-0316 BOLT41-2363 WASHER2-35-3800 NUT

10" (+/-1/4")

4-7/8" 7-3/16"

1-20 THREAD

STD MOTOR, 1/2 HP

3-1/2"

2"

41-0929 BUMPER2-02-5708 SCREW

41-0669 MTG. STRIP2-01-0312 BOLT

2-61-3100 WASHER

1-13/16"

FIG. 19 – MODEL 1402 VACUUM PUMP FOR YORK

SPECIFICATIONS:Free- Air Displacement, L/M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160

CFM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.6Guaranteed Partial Pressure

Blankoff, millitorr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.1Pump Rotational Speed, RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .525Number of Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Oil Capacity, qts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1/4Net Weight, Pump Only, lbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82Net Weight, Mounted Pump, lbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112Shipping Weight, Mounted Pump, lbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

LD05105A

LD05105B


SECTION 6 – BUFFALO PUMPS

INTRODUCTION

The Buffalo pumps used on IsoFlowTM chillers are sin-gle suction, single-stage, hermetically sealed centrifu-gal pumps designed for zero leakage, Totally ClosedLiquid Cooled (TCLC). The pumps employ a uniquespring-loaded conical bearing design that allows forlong life between overhauls. The pump bearings arecooled and lubricated by the pumping fluid (refriger-ant water or lithium bromide solution). The pumpingliquid also carries away heat generated by the motor.

Do not run the pump dry. Evenmomentary operation without thepump and motor casing filled withliquid will damage pump bearings.

Figure 20 shows a cutaway view of a single-endedpump. The arrows indicates the cooling circuitthrough the pump.

TROUBLESHOOTING

Pump Tripping on Overloads

Check voltage supply on all three phases to be sure itis correct for the pump motor in question. Check over-load for proper amperage setting (Pump Motor FLA),loose wires or poor connections that generate heat andtrip the overload. If no problems are found, shut off allpower to the unit, lock out and tag all disconnects.Check the motor connections to be sure the pump iswired correctly. Using a megohm meter, check thepump motor windings for shorts or grounds. If motorproblems are found, motor replacement will be neces-sary (Contact your local YORK Factory Serviceoffice for details). If no problems are found duringthis procedure, reconnect the motor. Apply power tothe unit and run the pump, while watching the operat-ing amps. If high amps are encountered, the problemmay be mechanical, such as bearing seizure. Pumpinspection will be necessary. If the overload continuesto trip, but the motor amperage is within the allowablerange, the overload is defective.

Pump Tripping on Thermal Protection

If the winding temperature thermostat is tripping thepump, allow the thermostat to reset. Exercise caution,the motor housing skin temperature should be inexcess of 300°F (148.9°C) when the winding temper-ature thermostat trips. Although rare, if the thermostatwill not reset in a reasonable period of time, it may bedefective. If this is the case, temporarily bypass thethermostat and run the pump. Check the motor hous-ing temperature with an infrared thermometer. Theaverage outside skin temperature of a solution pumpmotor housing is 190°F (87.8°C) at stable operatingconditions [100°F (37.8°C) Suction Temperature].Refrigerant pumps run cooler than this. Check to besure that the pump is not running dry periodically orthat either the suction/discharge isolation valves areclosed. Check to see that the pump is not pumpingabnormally high-temperature liquid for some reason.If no problems related to flow through the pump arefound, the internal coolant passages may be blocked.Pump disassembly will be required (Contact yourlocal YORK Factory Service office for details).

Unusual Noise/Vibration

Pumps will make some noise during normal opera-tion. If pump is experiencing cavitation, the noise andvibration will be more severe. Abnormal sounds andvibration may be due to foreign material trapped inthe coolant circuit and rubbing between the stator androtor. Noise may also be a result of extreme bearingwear. Pump disassembly is required.

Pump Overhaul

The expected time span between Buffalo Pump over-hauls on a properly maintained IsoFlowTM unit shouldbe between 50,000 and 60,000 hours. Pumps installedon units running with high amounts of suspendedsolids or high amounts of dissolved copper in thesolution will suffer shorter lives. It is therefore rec-ommended to install a solution filtration kit on theunit to remove the suspended solids and/or perform acopper removal procedure as indicated on the solutionchemistry report. Contact your local YORK FactoryService office for details.

FORM 155.16-OM1


FIG. 20 – FLOW OF REFRIGERANT WATER OR LITHIUM BROMIDE THROUGH PUMP

LD05

106A


SECTION 7 – STEAM AND WATER QUALITY CONTROL

GENERAL

Absorber/Condenser and Evaporator water must befree of corrosive species or inhibited to prevent attackof the waterside tubing. Impurities and dissolvedsolids can cause scaling that reduces heat exchangerefficiency and causes corrosion of tubes. Corrosion,in turn, can result in more serious problems, such asmetal wastage and contamination of the solution andrefrigerant if through-wall pitting occurs.

YORK IsoFlowTM Absorption Chillers can only deliv-er design output and efficiency if they are properlyoperated and maintained. One of the most importantelements of proper maintenance is the cleanliness ofthe tubes to prevent fouling, scaling and corrosionduring daily operations and shutdowns.

It is the responsibility of the owner (operator) of thisequipment to engage the services of an experiencedand reputable water treatment specialist for both theinitial charging of the system and its continuous mon-itoring and treatment. Improperly treated or main-tained water will result in decreased efficiency, highoperating costs and premature failure due to watersidecorrosion.

For water treatment programs to be acceptable, theymust protect all exposed metal (i.e., carbon steel, cop-per and brass) from corrosive attack. The use of cor-rosion inhibitors must be effective at low concentra-tions, must not cause deposits on the metal surfaces,and must remain effective under a broad range of pH,temperature, water quality and heat flux.Furthermore, the inhibitor package must prevent scaleformation and disperse deposits, while having a min-imal environmental impact when discharged.

Water samples should be collected and analyzed on atleast a monthly basis by the water treatment special-ist. A quarterly review with the treatment suppliershould address the conditions of the water systemsand develop action plans based on these analyses. Athird party water consulting company can help over-see the water treatment programs in order to properlyprotect the physical plant and avoid costly downtime.

It is equally important that the owner (operator) of theequipment performs tube cleaning and inspection ofthe absorber, condenser and evaporator watersidetubes at the frequencies recommended in the TubeBundle Section of the "Preventive MaintenanceSchedule" located in this manual. In addition to peri-odic cleaning with tube brushes, tubes must beinspected for wear and corrosion. Tube failures usual-ly occur due to corrosion, erosion, and fatigue due tothermal stress. Eddy current analysis and visualinspection by boroscope of all tubes are invaluablepreventative maintenance methods. These provide aquick method of determining waterside tube conditionat a reasonable cost.

Your local YORK Service Representative will bemore than happy to supply any or all of these services.

STEAM/CONDENSATE OR HOT WATER QUALITY

IsoFlow™ units use corrosion resistant CuNi tubes inthe generator.

As with the water side of the system, it is the respon-sibility of the owner (operator) of this equipment toengage the services of an experienced and reputablesteam/condensate or hot water treatment specialist forboth the initial charging of the system and its contin-uous monitoring and treatment. Improperly treated ormaintained steam/condensate or hot water will resultin decreased efficiency, high operating costs and pre-mature failure due to steam/condensate or hot waterside corrosion.

Steam/Condensate or hot water samples should becollected and analyzed on at least a monthly basis bythe treatment specialist. A quarterly review with thetreatment supplier should address the conditions ofthe steam systems and develop action plans based on these analyses. A third party consulting companycan help oversee the treatment programs in order toproperly protect the physical plant and avoid costlydowntime.

FORM 155.16-OM1


It is equally important that the owner (operator) of theequipment performs an inspection of the generatortubes at the frequencies recommended in the TubeBundle Section of the "Preventive MaintenanceSchedule" located in this manual. In addition to peri-odic cleaning with tube brushes, tubes must beinspected for wear and corrosion. Tube failures usu-ally occur due to corrosion, erosion, and fatigue dueto thermal stress. Eddy current analysis and visualinspection by boroscope of all tubes are invaluablepreventative maintenance methods. These provide aquick method of determining steam generator tubecondition at a reasonable cost.

Your local YORK Service Representative will bemore than happy to supply any or all of these services.

TUBE CLEANING

If during an inspection, scale is identified in any of thetube bundles, it will be necessary to remove this scaleto prevent operational and or corrosion problems.

A build-up of scale on the tubes can cause a widerange of problems including:

• Reduced chilling capacity

• High solution concentration and crystallization.

• Pitting and corrosion of tubes

• Reduced efficiency.

The first step in trying to clean scales from tubes is tobrush clean them. Only soft nylon brushes should beused, as damage to the copper or CuNi tubes willresult if harder brushes (such as steel) are used.

If the brush cleaning is unsuccessful in removing allthe scale from the tubes, it will be necessary to chem-ically clean them. An experienced and reputable con-tractor should be consulted. If the chemical cleaningis not performed properly, extensive tube damage mayresult.


SECTION 8 – UNIT OPERATING PROCEDURES

GENERAL

The YORK recommended installation of theseabsorption systems calls for complete automatic oper-ation. The system and all of the auxiliaries are con-trolled by a switch on the control panel or by a remotecontrol, such as a thermostat, time clock or otherexternal control.

It is recommended that Manual/Off/Automatic switches be used for con-trol of the condensing water pump,the chilled water pump, and thetower fan motor. However, it is cau-tioned that the chilled water pumpand the condensing water pumpmust always be operating when theunit is operating, and are thus pre-ferred in the "Automatic" position.This is necessary to (1) provide prop-er dilution of the solution, thus pro-tecting against crystallization duringshutdown, and (2) to avoid freezingup the evaporator tubes during unitoperation, including the dilutioncycle operation during which refrig-eration effect still occurs.

START-UP (NORMAL)

This start-up covers units that havepreviously been started.

See Form 155.16-O3, “Control Panel OperatorsManual” for detailed instruction on how to operate thepanel.

If the chiller has been idle for a long period of time,such as at the first start-up of the cooling season, itwill be necessary to check the internal pressure of theunit to ensure a smooth start-up. To do this, see thePurge section of this manual.

Refer to the chart in Fig. 21 to compare the saturationpressure within the unit to the equivalent plant roomtemperature. If the measured internal unit pressure iswithin the shaded area of the chart, the start-up maycontinue. If not, purge the unit until the internal unitpressure reaches the shaded area of the chart.

Open the main shut-off valves in condensing water,chilled water, and steam or hot water supply lines tothe system.

Close all disconnect switches to the control panel, thecooling water pump, chilled water pump, and towerfans.

Place the condensing water pump, chilled waterpump, and tower fan switches in the "Automatic"position. (If manual operation is required for specialconsiderations, refer to the NOTE under General).

40 60 80 100 120

PLANT ROOM TEMPERATURE ˚F

50

10

1

PR

ES

SU

RE

IN m

m H

g A

bs.

FIG. 21 – ACCEPTABLE INTERNAL UNIT PRESSURES

LD06021

FORM 155.16-OM1


SHUTDOWN (NORMAL)

Manual Shutdown (local operation)

See Form 155.16-O3, “Control Panel Operation”.

Move the Unit switch from the RUN to theSTOP/RESET position.

The Control valve will close and the unit will go intoa dilution cycle.

As there are many types of unit shutdowns possible,please refer to Form 155.16-O3, “Control PanelOperation” for a description of each.

OPERATING DATA

General

A complete set of data on operating temperatures andpressures should be recorded for the unit regularly(every week is suggested as optimum). The purpose isto permit early recognition of an abnormal conditionor trend that requires corrective maintenance, beforeserious damage occurs to the unit. Daily observationof the unit is useful to disclose any sudden changes.

All measurements that are recorded should be takenas simultaneously as possible with a steady load and asteady cooling tower water temperature, near thedesign conditions. A progressive gradual deteriora-tion in unit performance is an indication that scalingis occurring, that there is a gradual buildup of inerts orthat there is a malfunction of controls. It is mandato-ry that all performance analyses be based on date, andtaken on units that are free of leaks. Otherwise, thelithium bromide concentrations and the steam pres-sure and steam flow requirements for a given load, aswell as a complete set of operating temperatures, willbe abnormal.

A thorough check of system performance, includingsampling of the unit fluids, requires the services of aYORK Field Service Representative. He will takesamples of the refrigerant, the lithium bromidecharge, and the cooling water, as well as a completeset of operating data. He can assist in a complete per-

formance analysis and report on the condition of theunit. Samples can be analyzed and a complete reportobtained on the chemical content and pH levels. Theinvestment by the customer in the cost of these serv-ices is nominal compared to the cost of the unit andthe ultimate cost of repairs or increased operatingcosts, should the unit be inadequately maintained.

Inadvertent introduction of air into the unit by theoperator or the existence of leaks are to be avoided atall times for the attainment of long life of the unit. Theproper method of taking samples is tedious andrequires special training so that conclusions reachedconcerning the condition of the unit, the solutionchemistry and the cooling water are valid.

For greatest accuracy of the data taken on operatingunits, calibrated 1/5°F increment thermometersshould be used, particularly for measuring tempera-tures of chilled water and cooling water. Calibratedtest type pressure gauges and manometers also con-tribute to the attainment of accurate data. Accurateflow meters for water and steam condensate flow(with a subcooler) complete the instrumentationrequirements for the attainment of an accurate heatbalance. This instrumentation is not normally avail-able in the field. However, it can be obtained by spe-cial arrangements.

Nevertheless, a measure of the trend of system per-formance can be obtained by the systematic measure-ment of data taken with instrumentation normallyavailable in the field. In all cases, however, any analy-sis is only as good as the degree of accuracy of thedata taken. A steady state of operating conditions withall readings taken as simultaneously as possible,assists in obtaining valid data. All thermometers andpressure measuring devices should be calibrated sothat readings are corrected to the true values.Insulation placed around the pipe and the outside wellwill improve the accuracy and validity of readings.

With the assumption that all data taken are accurateand valid, the following method of analysis for sys-tem performance is recommended.


Performance Data and Calculations

Refer to the sample operating data sheet in Figure 22.This data is simulated by a computer for a YIA-6C4unit with nominal passes. The assumed operating con-dition is 80% of the design load rating with assumedfouling factors of .0005, .001 and .0015 in theabsorber and condenser, but with .0005 in the evapo-rator tubes. The effect of fouling on all readings isreadily apparent. This data also assumes that the 2-Ethyl-1-Hexanol additive is present in the unit atthe proper concentration to promote optimum shellside coefficients of heat transfer. This additive ischarged into the unit upon initial start-up, and rarelydoes more Hexanol have to be added. The effect ofHexanol additive on unit performance appears later inthis section.

The design load rating for the YIA-6C4 unit used forthe data simulation is as follows:

100% Design Load 517.9 TonsCondenser Water Flow 1870 GPMEntering Condenser Water Temp 85°FChilled Water Flow 1243 GPMChilled Water Range 54°F to 44°F

Passes - Chiller/Condenser/Absorber 2/1/1Fouling Factor for Absorber,

Condenser and Evaporator .0005Steam Pressure at Generator 9.2 PSIGSteam Flow 9478 lb/hrValve Inlet Steam Pressure 12PSIG =

299°FNormal Installation Ambient Pressure 29.5" Hg

(14.5 PSIA)Steam Source 15PSIG @ 300°F

Assume steam condensate is flashed at atmosphericpressure before it is weighed for test data purposes.

FORM 155.16-OM1


FIG. 22 – OPERATING DATA SHEET

LD04771


SECTION 9 – PTX CHART

READING THE PTX CHART(See Fig. 23)

The PTX chart (Pressure, Temperature, andConcentration chart) is an invaluable tool when itcomes to absorption cooling. It can be used for almostevery kind of troubleshooting situation, plotting solu-tion cycles through each heat exchanger, and deter-mining if air is within the system.

However, for this exercise the PTX chart will beexplained only for determining the concentration ofsolution samples.

Taking solution samples must onlybe done by a trained and qualifiedYORK Field Service Representative.

Determining the Solution Concentration:

The PTX chart shows Pressure in mm Hg. Absolute(horizontal lines), Temperature in Degrees Fahrenheit(vertical lines), and Solution Concentration in per-centages (diagonal lines). The PTX chart in Fig. 23 isfor single stage absorption machines because the tem-perature stops at 230°F. This is the highest expectedtemperature in the complete single stage absorptioncycle (in the generator). On the two stage absorptioncycle, the highest expected temperature will bearound 330°F. Notice the "Crystallization Area" is theright half of the chart and is to the right of the thick-est diagonal line.

For reading the PTX chart, two pieces of informationare required to obtain the third. The temperature is theeasiest to obtain and the pressure can be obtained viathe unit gauges. Use caution when using the unitmounted mercury manometer for checking the inter-nal unit pressure – DO NOT under any circumstanceslet air into the unit when checking the pressure. Seethe Purging section of this manual for the correctmethod to check the unit pressures. Looking at thePTX chart, follow the vertical temperature line andthe horizontal pressure line to where the two intersect.The closest diagonal line to this intersection would bethe correct solution concentration.

CRYSTALLIZATION

All absorption chillers that use lithium bromide andwater as the solution/refrigerant pair are subject to theperils of crystallization. This is due to the fact thatsome areas of the unit operate with solution liquidconcentration levels that are only possible at higherthan the normal ambient temperature surrounding theunit. For example, the solution concentration in thegenerator of a single stage absorption unit is typically64.3% lithium bromide by weight. Referring to Figure23, 64.3% solution will begin to crystallize at 100°F(37.8°C). Since the solution temperature in the gener-ator normally is higher than 200°F (93.3°C) at mostload conditions, no crystallization will occur as longas the higher solution temperatures are maintained.Special measures do have to be taken before the unitis shut down so that the solution is sufficiently dilut-ed in all areas of the unit to prevent crystallizationduring the off cycle, since the solution temperaturewill eventually equal the surrounding ambient tem-perature. All units employ some sort of dilution cycle,which fulfills this requirement. As long as the unit isallowed to dilute itself during an orderly shutdownsequence, the unit should be able to sit idle at fairlylow plant room ambient temperatures for extendedperiods of time without any threat of crystallization.Typically, after a dilution cycle, the average solutionconcentration within the chiller will be below 45%lithium bromide by weight. Although the crystalliza-tion line on Figure 23 does not extend that far, it canbe seen that the solution at 45% concentration willhave no tendency to crystallize at normal ambienttemperatures.

Why Does Crystallization Occur?

Probably the most predominant reason for crystalliza-tion is due to fairly long duration power failures. If achiller is running at full load and power is interruptedfor a sufficient length of time, the concentrated solu-tion in the high side of the unit will eventually cooldown. Since no dilution cycle was performed, thesolution concentration in some areas of the unit maystill be relatively high. If the temperature of this con-centrated solution is allowed to fall low enough, thesolution will reach its crystallization point. Plantroom temperature, insulation quality and the solutionconcentration all play a part in the determination ofhow long it will take before the unit will crystallize.

43YORK INTERNATIONAL 43AYORK INTERNATIONAL

FORM 155.16-OM1 FORM 155.16-OM1

20.3

.4

.5

.6

.7

.8

.91.0

2

3

WATER

4

5

6

7

89

10

20

30

40

50

60

70

80

90

20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230100

30 40 50 60 70 80 90 100 110 120

TEMPERATURE ˚F

PTX CHARTCRYSTALLIZATION AREA

TEMPERATURE ˚F

AB

SO

LU

TE

PR

ES

SU

RE

M. M

. M

ER

CU

RY

130 140 150 160 170 180 190 200 210 220 230

PERCENT OF CONCENTRATION (LI. BR. BY WEIGHT)65646362616059585756555453525150

454035302015100

64636261

60595857565554535251504540353020150 10

CRYSTALLIZATION LINE

66

FIG. 23 – PTX CHART

LD05216

YORK INTERNATIONAL

FORM 155.16-OM1

Power failures result in the unit pumps stopping com-pletely. Without the pumps inducing flow through thevarious sections of the unit, concentrated solutionbecomes trapped in the generator section and the solu-tion-to- solution heat exchanger. If this concentratedsolution is allowed to cool down to a low enough tem-perature, it may turn to a slushy liquid and eventuallyto a solid substance.

The potential for a YORK IsoFlowTM Chiller to crys-tallize during a power interruption is directly relatedto the following:

1. The concentration of the solution in the solutionheat exchanger is very important. The higher theconcentration at the time of power failure, themore likely the unit is to crystallize.

a. The higher the load, the higher the concentration.

b. A unit with dirty tubes or non-condensables will be more susceptible due to higher concen-trations in the solution heat exchanger.

c. Overfiring the unit will tend to over concen-trate the strong solution and make it more susceptible for crystallization.

2. The ambient temperature of the machine roomand the amount of thermal insulation on the solu-tion-to-solution heat exchanger will also deter-mine the likelihood of crystallization. Improper orinadequate thermal insulation on the hot sectionsof the unit will allow heat loss to progress rapidlyand therefore shorten the amount of time beforethe concentrated solution cools down to its crys-tallization temperature.

Outside air dampers that remain open during apower failure may allow the plant room to cooldown quickly, which will hasten crystallization.

3. The duration of the power interruption is veryimportant. Although it is very difficult to quantifythe acceptable time before crystallization occurs,it is doubtful that harmful crystallization willoccur if the power interruption is less than fifteenminutes. Thirty minute or longer power interrup-tions have been experienced during full load oper-ation of some machines with no problems.

Although a more rare occurrence, units can also crys-tallize during operation. Two of the chief causes ofcrystallization during operation are non-condensablesin the absorber and rapidly fluctuating tower watertemperatures.

Non-condensables in the Absorber

Non-condensables in the absorber result in less refrig-erant being absorbed by the solution. The solutionnever gets as diluted as it should. It leaves theabsorber and is heated in the generator. If the unit'sheat input is at or near full load, the leaving solutionconcentration may exceed the level at which it canremain liquid when passing through the solution-to-solution heat exchanger. For example, the normal con-centration of solution leaving the absorber at full loadis between 58% and 59.3%. If there are non-condens-ables present in the absorber, the solution concentra-tion may exceed 61%. Since the unit is attempting tooperate at full load, the firing rate will be sufficient toraise the solution concentration in the generator by atleast the same amount as when the absorber solutionwas normal, which was approximately 5%. Raisingthe solution concentration by 5% would result in 66%solution leaving the generator. Referring to the PTXchart in Figure 23, it can be seen that the crystalliza-tion temperature for 66% solution is approximately120°F (49°C). Since the generator temperature ishigher than 120°F (49°C), the solution will be okaywhile it is still in the generator. The problem occurswhen this over concentrated solution passes throughthe solution-to-solution heat exchanger on its wayback to the absorber sprays. Since this solution con-centration remains constant as it passes through thesolution-to- solution heat exchanger, if it is cooledbelow 120°F (49°C) at any point in the route, crystal-lization will begin. The cool solution leaving theabsorber is the solution-to-solution heat exchanger'smedium that cools the concentrated solution leavingthe generator as it passes on the shell side of the solu-tion-to-solution heat exchanger. This relatively coolsolution's temperature is the determining factor ofwhether crystallization occurs. Tower water inlet tem-perature will greatly affect the leaving solution tem-perature of the absorber. If the tower water tempera-ture is lower than design or is allowed to fluctuate ina downward trend fairly rapidly, the potential exists toover cool the concentrated solution in the solution-to-solution heat exchanger. Crystallization will thenresult.

To further compound this type of situation, if theabsorber is not performing well due to the presence of non-condensables, the amount of solution flowingto the generator will be less than normal since there is less refrigerant in it. Since the unit is attempting

43B

to make design capacity, the firing rate will be suffi-cient to raise the solution concentration higher thanthe design 5%. This will result in even higher solutionconcentrations leaving the generator. The temperatureof the solution leaving the absorber will also be lowerthan normal due to the amount of subcooling that willbe present as a result of the lack of mass transfer tak-ing place. This will result in a greater potential forover cooling the concentrated solution in the solution-to-solution heat exchanger.

Fluctuating Tower Water Temperature

Rapidly fluctuating tower water temperature can alsocause crystallization. The reasons are essentially thesame as described in the previous example. Rapidlyfalling tower water temperature will cause the leavingsolution temperature from the absorber to drop quick-ly. This cool solution may over-cool the concentratedsolution leaving the generator as it passes on the shellside of the solution-to-solution heat exchanger. Thiscan happen at normal generator solution concentra-tions, although, of course, the problem would be com-pounded if there were already abnormally high solu-tion concentrations in the generator.

Features That Will Help Prevent CrystallizationFrom Occurring

YORK IsoFlowTM chillers have several features thatwill help prevent crystallization from occurring. Theyare as follows:

1. The refrigerant charge is adjusted at full load, withno non-condensables present, so that refrigerant isjust ready to spill over the evaporator pan to theabsorber. Therefore, if the absorber ever begins tomalfunction due to the presence of non-condens-ables or dirty tubes, the solution concentration willincrease (less refrigerant present in solution).Consequently, the refrigerant quantity in the evap-orator pan will increase and begin to spill overinto the absorber solution, resulting in a concen-tration reduction.

2. For units with Eprom version A.02F.00:Whenever the unit is running, a feature calledStrong Solution Temperature Control is used. Themicro panel software continually monitors threedifferent temperatures throughout the system asfollows:

a. Refrigerant temperature leaving the condenser -(RTLC) at RT9.

b. Strong solution temperature at RT3.

c. Leaving chilled water temperature - (LCWT)at RT1.

RT9 and RT3 have operating ranges in relation-ship to each other for normal unit conditions. Ifthe strong solution temperature exceeds the allow-able limit, steam or hot water control valve load-ing is inhibited and the RTLC/strong solutiontemperature algorithm is enabled to slowly pulsethe valve closed, until the strong solution temper-ature is less than or equal to the limit. See YORKForm 155.16-O3 for details on this feature.

If the unit is equipped with Eprom A.02F.01:Low Entering Condenser Water Temp Load Limitreplaces the Strong Solution Temp Control and themicro panel will also monitor the Entering TowerWater temperature through RT5. After a 30 minutebypass at unit start, whenever the entering con-denser water temperature is less than 74°F(23.2°C), the maximum allowed steam/hot watervalve position is limited. Units equipped withEprom A.02F.02 and later: in addition to requir-ing the entering condenser water temperature to beless than 74°F (23.2°C), the strong solution tem-perature must be equal to or greater than the LowEntering Condenser Water Temperature(ECDWT) Solution temp override setpoint to per-form the control valve limiting to approximately60%. For more details on these features, seeYORK Form 155.16-O3.

3. The third type of crystallization prevention isthough the Automatic Decrystallization Cycle(ADC). Essentially, when crystallization starts tooccur, a blockage usually forms in the strong solu-tion side of the solution-to-solution heat exchang-er. This blockage inhibits the solution from flow-ing through the solution-to-solution heat exchang-er and the solution starts to back-up into the gen-erator. Solution starts to fill the generator outletbox and begins exiting through the ADC line.RT2, attached to the side of the ADC line sensesthe temperature rise in this line due to the hightemperature solution flowing through it. At 160°F(71.1°C) the micro panel will energize 2SOL(Stabilizer or decrystallize solenoid valve) toallow refrigerant to flow from the discharge of therefrigerant pump into the solution-to-solution heatexchanger, thus diluting the solution.


Measures to Prevent Crystallization

Good practices to help prevent crystallization shouldbe employed. These include:

1. Insulating the solution-to-solution heat exchang-er, generator solution outlet box and all intercon-necting piping.

2. Tower water (absorber cooling water) must be controlled to prevent rapid fluctuations intemperature.

3. Keep absorber, condenser and evaporator tubesclean.

4. Do not allow non-condensables to accumulate inthe unit. Proper purging techniques and solutionchemistry control will greatly reduce the likeli-hood of crystallization.

5. Be sure the refrigerant charge is adjusted so thatrefrigerant spill will occur if solution concentra-tions exceed the norm. Refrigerant may need tobe adjusted after several years of operation due tothe amount of refrigerant vapor removed duringpurging.

PRESSURE DROP CURVES

Figure 24 shows the pressure drops for the chilledwater, condenser water, and the hot water in relation-ship to the rate of flow in GPM. The absorber/con-denser includes 1 - 2 PSI pressure drop through thecross-over line. For construction of the cross-overline, see YORK Form 155.16-N3. The data shownare for pressure taps on the water boxes near theinlet and outlet nozzles. If pressure gauges are usedto determine pressure drop, they should be calibratedso that maximum efficiency is obtained. Also, a cor-rection for static head difference must be made if the

FORM 155.16-OM1


gauges are not located at the same elevation or level.The conversion from PSI to ft. of water is 2.31 ft. for1 PSI.

REFRIGERANT CONCENTRATION

Operation at low loads and low condensing watertemperatures will cause solution to be brought over tothe refrigerant circuit to sustain operation and avoidextensive cavitation of the refrigerant pump. At suchtimes that a system analysis is conducted at high loadand high condensing water temperature, the solutionin the refrigerant circuit would have been appreciablydiluted, by virtue of the full evaporator pan that devel-ops. With the effect of blowdown and possibly somespillover, the refrigerant concentration level is proba-bly very near 1.00 S.G. Considering the intent of ananalysis, it may be desirable to route some of therefrigerant back to the absorber via the refrigerantvalve (2 SOL) to establish a still cleaner refrigerant.For refrigerant blowdown, see "Control ComponentsExternal To The Control Center" for this operation.

During refrigerant blowdown, stopthe refrigerant pump immediatelyon pump cavitation noise or fromindications on a pressure gauge on pump discharge (fluctuatingwildly).

At minimum loads (10%) and minimum condensingwater temperature, the concentration in this circuitcould reach 35 to 40% by weight lithium bromide. Asthe load increases and the pan fills, this concentrationwill diminish and eventually be very slight or non-existent.


PRESSURE DROP CURVESMODEL YIA – 1A1 MODEL YIA – 1A2

LD01506

LD01508

LD01507

LD01509

LD01510

LD01511

1

2

5

10

20

90 100

200

300

400

500

1 PAS

S

2 PASS

3 PASS

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

10

4030

20

2

5

7

200

300

400

500

600

700

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*

1

2

4

6

10

20

30

50

70

100

200

300

400

500

700

1000

1600

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PAS

S

2 PAS

S3 PAS

S4 PAS

S

1

2

3

5

7

10

20

30

90 100

200

300

400

500

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS

3 PASS

1

10

5

3

GPM

TOWER WATER

7

20

30

50

200

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

300

400

500

600

700

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

CONDENSER

*

* See Notes on page 56.

FIG. 24 – PRESSURE DROP CURVES

FORM 155.16-OM1


MODEL YIA – 2A3 MODEL YIA – 2A4

LD01512

LD01513

LD01514

LD01515

LD01516

LD01517

1

2

3457

10

20

3040

6080

100

200

300

400

500

700

1000

1600

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PAS

S

2 PAS

S3 PAS

S4 PAS

S

1

2

3

45

7

10

20

30

90 100

200

300

400

500

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS

3 PASS

1

2

3

5

7

10

20

30

50

200

300

400

500

600

700

800

1000

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

CONDENSER

*

1

2

3

5

7

10

20

3040

6080

100

200

300

400

500

700

1000

1600

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS

3 PASS4 P

ASS

1

2

3

456

810

20

30

90 100

200

300

400

500

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS

3 PASS

1

2

34

68

10

20

4030

60

200

300

400

500

600

800

1000

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*

* See Notes on page 56.FIG. 24 – PRESSURE DROP CURVES (CONTINUED)

MODEL YIA – 2B1 MODEL YIA – 3B2

1

2

3

5

7

10

20

3040

6080

120

200

300

400

500

600

800

2100

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01518

100

200

300

400

500

650

1

2

3

456

810

20

30

40

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS

3 PASS

LD01519

200

300

400

500

600

700

800

1000

1100

ABS/COND 2/1 P

ASS

ABS/COND 1/1 P

ASS

ABS/COND 3/1 P

ASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

2

345

7

10

20

3040

60

CONDENSER

*LD01520

1

2

3

5

7

10

20

3040

6080

120

200

300

400

500

600

800

2100

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PAS

S

2 PASS3 P

ASS

4 PASS

LD01521

1

2

3

456

810

20

30

40

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS

3 PASS

100

200

300

400

500

650

LD01522

ABS/COND 2/1 PASS

ABS/COND 1/1 PASSABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

2

345

7

10

20

3040

60

375

500

600

700

800

900

1000

1500

CONDENSER

*LD01523


FIG. 24 – PRESSURE DROP CURVES (CONTINUED)


FORM 155.16-OM1


MODEL YIA – 3B3 MODEL YIA – 4B4

1

2

3

5

7

10

20

3040

6080

120

200

300

400

500

600

800

2100

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01524

1 PA

SS

2 PAS

S

3 PAS

S

100

200

300

400

500

650

2

3

4

56

8

10

20

30

40

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

LD01525

1

2

345

7

10

20

3040

60

375

500

600

700

800

900

1000

1500

ABS/COND 2/1 PASS


GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01526

1

2

3

5

7

10

20

3040

6080

120

200

300

400

500

600

800

2100

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01527

2

3

4

56

8

10

20

30

40

1 PA

SS

2 PAS

S

3 PAS

S

100

200

300

400

500

650

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

LD01528

1

2

3457

10

20

3040

65

375

100090

0

800

700

600

500

1500

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

ABS/COND 1/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01529




MODEL YIA – 4C1 MODEL YIA – 5C2

1

2

3

5

7

10

20

3040

6080

200

300

400

500

600

800

3000

2000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01530

150

200

300

400

500

600

800

1000

2

3

4

56

8

10

20

30

40

1 PA

SS

2 PA

SS

3 PA

SS

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

LD01531

1

2

345

7

10

20

3040

65

400

500

600

700

800

900

1000

1600

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01532

1

2

3

5

7

10

20

3040

6080

200

300

400

500

600

800

3000

2000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01533

2

3

4

56

8

10

20

30

40

1 PA

SS

2 PA

SS

3 PA

SS

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

150

200

300

400

500

600

800

1000

LD01534

1

2

3457

10

20

3040

65

500

600

700

800

900

2200

2000

1000

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01535



FORM 155.16-OM1


MODEL YIA – 5C3 MODEL YIA – 6C4

1

2

3

5

7

10

20

3040

6080

200

300

400

500

600

800

3000

2000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01536

1

2

3457

10

20

3040

65

500

600

700

800

900

1000

2000

2200

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01538

2

3

4

56

8

10

20

30

40

1 PAS

S

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

150

200

300

400

500

600

800

1000

LD01537

1

2

3

5

7

10

20

3040

6080

200

300

400

500

600

800

3000

2000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01539

2200

1

2

3457

10

20

30

50

70

100090

0

800

700

600

500

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

ABS/COND 3/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01541

150

200

300

400

500

600

800

1000

2

3

4

56

8

10

20

30

40

50

1 PAS

S

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

LD01540* See Notes on page 56.



MODEL YIA – 7D1 MODEL YIA – 7D2

1

2

3

5

7

10

20

3040

6080

250

400

500

600

800

4200

2000

3000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01542

200

300

400

500

600

700

800

1000

1200

2

3

4

56

8

10

20

30

40

1 PAS

S

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

LD01543

LD01544

1

2

3

5

7

10

20

3040

6080

250

400

500

600

800

4200

2000

3000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01545

2

3

4

56

8

10

20

30

40

50

1 PA

SS

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

200

300

400

500

600

700

800

1000

1200

LD01546

1

2

3457

10

20

30

50

70

800

900

1000

2000

3100

ABS/COND 1/1 PASS


GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*

800

900

1000

2000

3100

1

2

3457

10

20

30

50

70

TOTAL 1 PASS

TOTAL 2 PASSTOTAL 3 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

CONDENSER

*LD01557



FORM 155.16-OM1


MODEL YIA – 8D3 MODEL YIA – 8E1

1

2

3

5

7

10

20

3040

6080

250

400

500

600

800

4200

2000

3000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01547

2

3

4

56

8

10

20

30

40

50

1 PAS

S

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

200

300

400

500

600

700

800

1000

1200

LD01548

800

900

1000

2000

3100

1

2

3457

10

20

30

50

70

ABS/COND 1/1 PASS


GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

CONDENSER

*LD01549

1

2

3

5

7

10

20

3040

6080

300

400

500

600

800

5500

2000

3000

4000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01550

2

3

4

56

8

10

20

30

40

1 PA

SS

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

300

400

500

600

700

800

1000

1700

LD01551

1000

2000

3000

4000

4500

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

2

3457

10

20

30

50

70

CONDENSER

*LD01552




MODEL YIA – 9E2 MODEL YIA – 10E3

1

2

3

5

7

10

20

3040

6080

300

400

500

600

800

5500

2000

3000

4000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01553

2

3

456

810

20

30

40

50

1 PAS

S2 PASS

3 PASS

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

300

400

500

600

700

800

1000

1700

LD01554

2

3

456

810

20

30

40

50

1 PAS

S2 PASS

3 PASS

GPM

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

300

400

500

600

700

800

1000

1700

LD01555

1

2

3

5

7

10

20

3040

6080

300

400

500

600

800

5500

2000

3000

4000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

4 PASS

LD01494

2

3

456

810

20

30

40

50

1 PASS2 P

ASS

3 PASS

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

300

400

500

600

700

800

1000

1700

LD01595

1000

2000

3000

4000

4500

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

2

3457

10

20

30

50

70

ABS/COND 2/1 PASS

ABS/COND 1/1 PASS

CONDENSER

*LD01496



FORM 155.16-OM1


MODEL YIA – 12F1 MODEL YIA – 13F2

1

2

3

5

7

10

20

3040

6080

500

700

7000

2000

3000

4000

5000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

LD01497

2

3

456

810

20

30

40

50

1 PASS

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

400

500

600

700

800

1000

2000

2500

LD01498

LD01499

1

2

3

5

7

10

20

3040

6080

500

700

7000

2000

3000

4000

5000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

LD01500

2

3

456

810

20

30

40

50

1 PASS

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

400

500

600

700

800

1000

2000

2500

LD01501

1500

2000

3000

4000

5000

6000

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

2

3457

10

20

30

50

70

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

CONDENSER

*LD01502




MODEL YIA – 14F3

* Pressure drop curve for the condenser water circuit onlyis shown as a dotted line. For total tower water pressuredrop through the chiller use the appropriate solid line.For example, a chiller with a 2-Pass absorber and a 1-Pass condenser, use the “ABS/COND 2/1 curve.”

1

2

3

5

7

10

20

3040

6080

500

700

7000

2000

3000

4000

5000

1000

GPM

CHILLED WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1 PASS

2 PASS3 P

ASS

LD01503

2

3

456

810

20

30

405060

1 PASS

2 PAS

S

3 PAS

S

GPM

HOT WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

400

500

600

700

800

1000

2000

2500

LD01504

1500

2000

3000

4000

5000

6000

GPM

TOWER WATER

PR

ES

SU

RE

DR

OP

–FT

. WA

TE

R

1

2

3457

10

20

30

50

70

ABS/COND 1/1 PASS

ABS/COND 2/1 PASS

CONDENSER

*LD01505


* Pressure drop curves include 1 psi pressure drop forcross-over line.

FORM 155.16-OM1


SECTION 10 – PREVENTATIVE MAINTENANCE – TUBES

CLEANING AND MAINTAINING THE TUBES WITHIN THE SHELLS

Tubes

The necessity for tube cleaning will be indicated by adrop in capacity or other symptoms. The frequency ofcleaning will vary as influenced by local water char-acteristics, atmosphere contamination, operating con-ditions, etc.

In many major cities, reliable commercial organiza-tions are now available which offer a specialized serv-ice of cleaning water sides of pressure vessels. Theseorganizations will analyze the type of dirt or scale tobe removed and then use the proper cleaning solutionfor the specific job.

Tube fouling is commonly due to deposits of twotypes as follows:

1. Dirt, rust or sludge which is carried from someother part of the system into the tubes. This mate-rial does not usually build up to coat the entiretube surface, but lies in the bottom of the tubes.When this accumulation of sludge is greatenough, water flow through the tubes will berestricted and the heat transfer surface will bereduced. This type of tube fouling is easily visibleand can be removed by a thorough brushing witha soft bristle bronze brush as outlined under"Brush Cleaning of Tubes".

2. Scale is a hard layer of mineral deposit which pre-cipitates out of the water and forms a hard coatingon the inside surfaces of the tubes. This coating isoften invisible but always highly resistant to heattransfer.

The most common types of scale found within thetubes are calcium carbonate, calcium sulphate andsilica, although other scales do form, dependingupon local water conditions. Since scale is usual-ly invisible when tubes are wet, it is better to blowthe water out of the tubes and allow the tubes to

thoroughly dry before checking for scale. Afterthe tubes have thoroughly dried, calcium scalewill usually show up as a white coating inside thetube (silica scale may not show up at all); but thescale can usually be flaked off of the inside of thetube with a small knife.

The only positive method of identifying a scale isa chemical analysis, although an analysis of thewater used in a specific system will indicate thetype of scale which may be expected to form.

Although other good commercial cleaning agentsare available for removing a specific scale, facto-ry experience has been obtained chiefly withcommercial inhibited hydrochloric (muriatic)acid, which has proven to be a good cleaningagent for most scales.

When it becomes necessary to clean condenser tubes,the absorber tubes should also be cleaned. If thechilled water system is kept clean during installationand is filled with clean water, it should not be neces-sary to clean the evaporator tubes, except if coolingwater is used in an air washer. The lines to the purgedrum and its coil must be acid cleaned when coolingcircuit is cleaned.

BRUSH CLEANING OF TUBES

If tube fouling consists of dirt and sludge, it can usu-ally be removed by means of the brushing process.Drain the water sides of the circuit to be cleaned(cooling water or chilled water), remove the headsand thoroughly clean each tube with a soft bristlebronze brush. DO NOT USE A STEEL BRISTLEBRUSH. A steel brush may damage the tubes.

Improved results can be obtained by admitting waterinto the tube during the cleaning process. This can bedone by mounting the brush on a suitable length of1/8" pipe with a few small holes at the brush end andconnecting the other end by means of a hose to thewater supply.


TROUBLESHOOTING TABLE

SYMPTOM POSSIBLE CAUSE CORRECTIVE ACTION

1. ABSORPTION UNIT A. Power supply and unit fuses. Replace if necessary.WILL NOT START B. Flow switches open. Check chilled water and cooling tower pumps.

C. Starter overloads open. Push reset buttons of both starters.

D. Motor coolant float switch open. Contact local district office for service.

2. UNIT CYCLING OR A. Air in water piping causing varying Purge air from the water piping.ERRATIC CHILLED water flow to the unit.WATER B. Control valve not functioning Check actuator and linkage. Adjust if necessary.TEMPERATURE properly (not closing). Check max. rate setting normal 1.0.

C. Low temperature thermostat Check cutout setting using 1/5°F thermometernot cutting out at correct setting 39°F. (If not working properly, contacttemperature settings. local district office.)

D. Fluctuating steam pressure or Correct supply source.hot water temperature.

E. Cooling water temp. cycling Readjust settings.improper tower fan setting.

3. UNIT NOT MAKING A. Air in unit.CAPACITY a. Improper purging See “Purge System Operation” section for proper

procedure for purging.

b. Purge pump malfunctioning. See “Purge Pump Maintenance” section for servicinginformation.

c. Leak in unit. Contact local district office for service.

B. Cooling (Tower) water GPM Set to correct quantity using design pressure dropbelow design. for your unit.

C. Insufficient steam to the Check supply. Readjust steam valve and regulatinggenerator flange. valves, if necessary.

D. Condensate backup into Check steam trap float and/or valves. generator tubes.

E. Tube fouling excessive. See “Preventive Maintenance” section for propermethod of cleaning tubes.

F. Crystallization

a. Air in unit See “Purge System Operation” section for properprocedure for purging.

b. Improper dilution cycle. Check float operation. Check dilution time operation.See that condenser water and chilled water pumpsrun until completion of dilution cycle.

G. Cooling tower water temperature Readjust setting or replace controller and/or fan fluctuating rapidly. thermostats as necessary.

H. ADC circuit malfunction. Check sensor and 2SOL refrigerant solenoid forproper operation.

I. Steam pressure too high. Check setting of pressure reducing valve, if used.Adjust steam valve to reduce maximum opening..

4. PURGE PUMP INCA- A. Contaminated oil. Change oil as recommended.PABLE OF PULLING B. Ballast valve cracked or scored. Repair with kit listed in “Renewal Parts” list.BELOW 1MM

C. Malfunctioning pump. Repair or replace.

5. PURGE PUMP OIL A. Faulty shaft seal rubber. Repair with kit in “Renewal Parts” manual.LEAKAGE

FO

RM

155.16-OM

1

59Y

OR

K IN

TE

RN

AT

ION

AL

Component Preventative Maintenance OperationMaintenance Interval (Months unless otherwise indicated)

See Note Below As Needed Daily Monthly 4 6 12 24 36 48 60Unit Solution Chemistry Analysis

(1), T(Add inhibitors as needed)

Record Operational Data (Data Form) OLeak Test Unit (2)Check Electrical Connections TReplace Sight Glasses or Glass Gaskets TCheck For Proper Solution Levels,

Tadjust as required

Check For Proper Refrigerant Levels,T

adjust as requiredCheck For proper Concentration of

TOctyl Alcohol

Check Unit Level and/or Pitch T

(Steam Units)Unit Safety Controls LRT - Low Refrigerant Temperature

T- Performance Test Cutout Switch

CHFLS - Chilled Water Flow Switch. TCWFLS - Condenser Water Flow Switch THT1 - High Temperature Cutout Switch T

Instrumentation Accuracy check of thermistorsT

and transducersAccuracy check of Condenser

TPressure Gauge (if applicable)

Solution and Inspection (pump bearing and seal wear) (3) T

Refrigerant Pumps Rebuild as required.Inspection of pump contactors

Tand overloads

Check operating amperage of pumps. O TCheck electrical connections to pumps TCheck performance of pumps T

(pressures, etc.)Check average skin temperatures T

of pumps

PR

EV

EN

TAT

IVE

MA

INT

EN

AN

CE

SC

HE

DU

LE

YO

RK

INT

ER

NA

TIO

NA

L60

Component Preventative Maintenance OperationMaintenance Interval (Months unless otherwise indicated)

See Note Below As Needed Daily Monthly 4 6 12 24 36 48 60Purge Pump Inspection of belt - replace or tighten

Oas needed

Check operating amperage of pump OCheck electrical connections to pump TInspection of pump contactor

Tand overload

Change oil ODetermine ultimate vacuum of pump TRebuild or replace pump T

Purge System Rebuild Purge Diaphragm Valves TAccuracy check of manometer or

TVacuum Gauge

Tube Bundles Clean tubes in absorber, condenser,evaporator & hot water heat exchanger T

(where applicable)Eddy current inspection (4)

Steam (Steam-Fired Inspection for wear of steam valve - T

Units only) Rebuild or replace as neededCheck for proper steam valve

Tmodulation

Inspect steam system piping andO

components for leaksInspect for design steam entering

Oconditions

NOTES:1. Units that provide year-round cooling: Once every four months, and as required due to excess purge requirements.

Units that provide only seasonal cooling: Once at the beginning of the cooling season, once in the middle, and as needed due to excess purge requirements.2. Units should be leak-tested when excessive purging is required. Note: The solution chemistry should always be checked (and adjusted as necessary) prior to performing a leak test.3. More frequent rebuilds will be required if solids and/or dissolved copper is present in the solution.4. Perform every 2-3 years or as required.

T = YORK Qualified Service TechnicianO = Operator

FORM 155.16-OM1


tallized heat exchanger from the opposite side of thetubes and causes the crystallized lithium bromide todissolve back into solution.

Blowdown:

While running the unit, refrigerant is intentionallydumped into the absorber shell section by opening2SOL (stabilizer solenoid valve). A refrigerant blow-down will further dilute the solution in the absorbershell. A blowdown is required before taking a solu-tion sample for analysis, to separate the alcohol from the refrigerant, and to hasten the refrigerant clean-upprocedure.

C.O.P.:

Coefficient of performance. A means of comparingthe performance of a chiller as the ratio of the coolingoutput divided by the heat input.

Concentration:

The percent by weight of lithium bromide present insolution. New solution is sent with a concentration of54% if the inhibitor is ADVAGuard 750, or 55% if theinhibitor is molybdate.

Condensate:

Condensed steam leaving the unit.

Condenser:

Vapor produced by the generator enters the condenserand is cooled and condensed back into a liquid by thetower water flowing through the inside of the con-denser tubes. The condensed vapor liquid drips downinto a collection pan located at the bottom of the con-denser. From there it flows out of the pan, through anorifice, and into the evaporator.

Condenser (Tower) Water:

The external water loop which is used to remove heatfrom the unit. This water passes first through theAbsorber, then the Condenser. Typical temperaturesare entering the Absorber at 85°F, leaving theAbsorber (entering the Condenser, i.e. crossover) at92°F, and leaving the Condenser at 95°F. Some exter-nal means of removing this heat is necessary.Typically a cooling tower is used for this application.

GLOSSARY OF TERMS

Absorber:

The concentrated solution coming back from the gen-erator is pumped to a solution spray header where it issprayed over the tubes in the absorber. Refrigerantvapor is absorbed into the solution and the solution isthus diluted. This diluted solution is collected at thebottom of the absorber where it is again pumped tothe generator.

ADC Flush Line:

This line runs between the solution pump dischargeand the ADC line. When the solution pump runs,weak solution is constantly supplied to the ADC line.This keeps the ADC line from crystallizing, due to itbeing exposed to the low pressures generated withinthe absorber while the unit is running.

ADVAGuardTM 750:

YORK's newest Inhibitor. An inorganic inhibitor pro-viding excellent corrosion protection to the unit'sinternal steel and copper surfaces. Also see Inhibitor.

Alcohol (2-Ethylhexanol):

A liquid added to an absorption chiller to enhance theheat and mass transfer in the Absorber. It is an octylalcohol whose chemical name is 2-Ethyl-1-Hexanol(C8H18O) with a molecular weight of 130.2, a boil-ing point of 364.3°F, and a flash point of 177.8°F @760 mmHg. Having a colorless, clear appearance, ithas a somewhat pungent odor. By adding 2-Ethylhexanol to the absorption cycle, overall unit per-formance increases by 5-15%. In addition, cycle tem-peratures, pressures, and concentrations tend todecrease with the addition of 2-Ethylhexanol.

Automatic De-crystallization Pipe (ADC):

The automatic de-crystallization pipe is a U-shapedline coming off the generator solution outlet box andterminating in the absorber shell. During normal unitoperation, this line has no flow in it. If crystallizationwere to occur, it would normally be in the strong solu-tion side of the heat exchanger. This blockage wouldback up solution into the generator solution and intothe automatic de-crystallization pipe. Once the hotsolution goes into the ADC pipe, it bypasses the heatexchanger and goes directly into the absorber shell,thus heating the solution in the absorber shell. Theheated solution in the absorber then heats up the crys-


Crystallization:

Under certain conditions, lithium bromide solutionmay increase in viscosity and become slush-like, oreven solidify. The likelihood of solution crystallizingincreases as the concentration increases and/or thetemperature decreases. For reference, here are somepoints where the liquid solution of lithium bromidewill crystallize, assuming a saturation condition:240°F @ 70%; 207°F @ 69%; 182°F @ 68%; 158°F@ 67%; 138°F @ 66%; and 120°F @ 65%. Typically,crystallization occurs where the heated, high concen-trated solution leaves the generator and passes throughthe heat exchanger. This is where the solution is at itshighest concentration that meets the lowest tempera-ture. Under normal running conditions, crystallizationis not a problem. Extreme cold ambient temperatures,power failures, and unit air leakage are the typicalcauses for crystallization.

Dilution Cycle:

Intentionally running the solution, refrigerant, towerwater, and chilled water pumps after unit has beenshut down to allow the concentrated solution tobecome more dilute. Essentially, the cycle continueswithout the addition of heat, thus, slowly diluting thesolution to concentration levels where it is more diffi-cult to crystallize. The dilution cycle will shut off afterthe solution temperature reaches 136°F. Note: Thedilution cycle is dependent upon many factors.Please see the micropanel instructions for details.

Eductor:

An eductor is a liquid-powered jet pump. Jet pumpshave no moving parts and use a high-pressure streamof liquid to pass through a nozzle, causing a portion ofof a low-pressure stream coming into the side of thepump to combine with the nozzle stream. This causesa reduction in pressure at the low-pressure inlet andinduces the rest of the low-pressure inlet substance toflow into the body of the pump.

On IsoFlowTM units, an eductor is used in place of acentrifugal pump to induce strong concentrated solu-tion exiting the generator outlet box to combine withweak concentrated solution exiting the solution pumpdischarge, before going to the absorber spray header.

Evaporator:

The section of a chiller that is responsible for remov-ing the heat from the chilled water circuit, thus cool-

ing the chilled water to be used to cool a building, amanufacturing process, or whatever application it isintended. Typically, the chilled water is cooled from54°F to 44°F. In an absorption chiller, the pure refrig-erant generated in the generator is cooled and con-densed in the Condenser and supplied to theEvaporator. Here, it is immediately exposed to amuch lower pressure which causes some immediateflashing (boiling). Most of the refrigerant cools to thesaturation temperature and remains in liquid form. Itis then pumped and sprayed over the Evaporator tubebundle. As the refrigerant passes over the outer sur-face of the tubes, it evaporates (i.e. flashes or boils)because of the low pressure, approximately 5.5-6.5mmHg which is equivalent to a saturation temperatureof 36-41°F. The refrigerant vapor is then immediate-ly drawn through the eliminator towards the Absorber.This vacuum is caused by the hygroscopic action, theaffinity Lithium Bromide has for the refrigerant vapor.

Evaporator Sprays:

A series of spray nozzles that evenly distribute refrig-erant from the refrigerant pump discharge to the evap-orator section tubes.

Float (1F), (3F):

There are two floats that sense liquid levels on theIsoFlow units. Both are located in the refrigerant cir-cuit. Float (1F) is at the side of the evaporator refrig-erant outlet box, and senses the level in the box. Atlow levels in this box, the 1F float will open, causingthe micropanel to initiate corrective procedures tokeep the unit from running out of refrigerant. Formore details, see YORK Form 155.16-O3.

Float (3F) is located just before the inlet of the Buffalorefrigerant pump. It's main purpose is to keep theBuffalo pump from cavitation and eventual overheat-ing. For more details on the operation of this float, seeYORK Form 155.16-O3.

Generator:

This component of the absorption system heats dilut-ed lithium bromide solution coming from the absorbershell. The generator can receive its heat source fromeither hot water to 266°F (130°C) and 300 PSIG orsteam of up to 337°F (169°C) and 15 PSIG. As thesolution is heated, refrigerant vapor is boiled off andrises to the condenser. The resulting concentratedlithium bromide solution flows back to the absorbersprays.

FORM 155.16-OM1


G.P.M.:

A measure of volumetric flow rate (Gallons PerMinute).

Hot Water Valve:

The capacity control valve that regulates the amountof hot water to the generator (hot water units only).

Inhibitor:

A chemical used to help minimize or inhibit the cor-rosion of the internal steel surface area of the unit. Itworks by chemically slowing down the natural ten-dency of steel to oxidize or corrode. YORK's currentinhibitor is Lithium Molybdate (Li2MoO4) andADVAGuardTM 750.

Insulation:

Units should be insulated in the field according to theinstallation manual. Insulation should be installed fora variety of reasons:

1. Decreases the heat loss through the walls of thevessel to its surroundings, thus increasing the effi-ciency of the machine.

2. Helps reduce the potential of crystallization in theevent of a power failure.

3. Burn protection for operating personnel in hightemperature areas.

4. Eliminates condensation on low temperatureareas of the machine.

IsoFlowTM

Our trademark name for a single-stage absorptionunit.

Isolation Valve:

One isolation valve is located at each Buffalo Pumpinlet and outlet. It is a positive sealing, butterfly typevalve mounted between standard ANSI flanges. Eachvalve incorporates an EPDM liner on the valve face toact as a sealing surface. When closed, the valves willisolate the unit vacuum from the pump area to offerease of serviceability when working on the pumps.

Micropanel:

The "brains" of the unit. The micropanel is the elec-tronic control panel which instructs the entire unit onwhen and how to run. Integrated into the logic of the

micropanel are sensors to measure key temperaturesand pressures which are then used to monitor real-time conditions.

Model Number:

A series of abbreviations or designations used to iden-tify IsoFlow™ units.

Molybdate:

(Lithium Molybdate, Li2MoO4). The current corro-sion inhibitor used for York’s absorption units. Bychemically slowing down the natural tendency ofsteel to oxidize or corrode, the inhibitor is supplied insolution with the Lithium Bromide. See alsoInhibitor.

Non-Condensables:

A gaseous substance that cannot be liquified or con-densed at the pressure and temperature surrounding it.The presence of non-condensables in the unit cancause severe performance problems. Non-condens-ables appear in two forms in the unit: 1. Internallygenerated non-condensables are formed as a by-prod-uct of corrosion; 2. Air may be drawn into a unit vialeaks.

Non-condensables that collect in the absorber sectionof the unit blanket the heat transfer tubes and raise theinternal pressure, thus reducing the absorber’s abilityto capture the refrigerant vapor. Non-condensablesthat collect in the high side of the unit end up in thecondenser section, where they blanket the condensertubes, reducing the condenser’s capacity.

It should be noted that the only non-condensable thatis not self-generated by the chemistry inside the unitis nitrogen. Air is over 70% nitrogen; an air leak is theonly external source of nitrogen. All other non-con-densables are generated by various chemical reactionsthat occur internally for many different reasons.

Oil Trap:

The oil trap is located between the purge pump suc-tion connection and the unit. It is designed so it willhold one complete oil charge of the vacuum pump. Inthe event air was to get into the unit through the vac-uum pump, the low pressure in the absorber wouldinduce the oil onto the system. Therefore, the oil trapis used as a safety measure to protect the absorptionunit from the oil.


Orifice:

A restriction in a liquid line for the purpose of reduc-ing the internal diameter of the line. Usually createdby a blank piece of metal with a small hole drilled intoit, to create a pressure differential when a liquid pass-es through it.

Pass Baffle:

A division plate or plates (baffles) inserted into awater box to create chambers which force the water topass through different portions of the tube bundle,called passes. Although the pressure drop increaseswith increasing passes, the tradeoff for heat transferoptimization and nozzle locations are justified.

Power Panel

The power panel serves as single-point wiring loca-tion for the unit’s incoming power wiring. It housesall the unit pump contactors and overloads, as well asfuses and terminal lugs for ease of serviceability. Atransformer is included to reduce the incoming unitvoltage to the required control voltage to themicropanel.

Pressure Drop:

The amount of pressure decrease experiencedbetween two locations. Often referred to whendescribing the drop in pressure found while passingwater through the tubes in a chiller. Typically meas-ured in PSI or Ft H20

Purge Drum:

The purge chamber is also sometimes called the purgedrum. It was designed to produce a low-pressure areaso that non-condensables can be pulled out of theabsorption system and expelled to the atmosphere bythe purge pump.

The purge drum functions similar to the way that theabsorber section of the system functions. Tower watercirculates through a coil inside the purge drum whilesolution is sprayed over the outside of the coil. Thisprocess induces the non-condensables in the absorbershell to enter a purge header assembly with the shell and migrate to the purge drum. Once inside thepurge drum, the vacuum pump can pull the non-con-densables out of the drum and expel them to theatmosphere.

Purge Pump:

An external pump connected to the purge system ofthe unit. This pump is used to evacuate non-con-densables from the unit.

Purging:

A process by which non-condensables present in aunit are removed through the use of a vacuum pump.

Refrigerant:

(Water, H2O). Deionized water is used as the refrigerant.

Refrigerant Anti-Freeze Line:

This line runs between the outlet of the refrigerantpump and the refrigerant condensate line(s) comingdown off the condenser. When the refrigerant pump isoperating, a constant supply of refrigerant is suppliedto mix with the refrigerant coming from the condens-er to keep it from freezing during low loads and lowcondenser water temperatures.

Refrigerant Pump:

A hermetically sealed, centrifugal pump locateddownstream of the evaporator outlet box. This pumpreceives liquid refrigerant from the evaporator anddischarges it back up to the evaporator sprays. It con-tinues to re-circulate the refrigerant while the chilleris operational.

Rupture Disk (Hot Water Units Only):

Although IsoFlowTM absorption units operate at lessthan atmospheric pressure (a vacuum), if certainsafeties fail and/or incorrect valves are closed, the unitcould experience higher pressures in certain cham-bers. Therefore, a pressure relief apparatus, a rupturedisk, is added.

Sight Glass:

A leak tight port hole used to visually inspect liquidlevels within the unit. A threaded design with aquartz glass window is presently being used.

Solution:

A mixture of deionized water with a certain % byweight of dissolved lithium bromide (LiBr).Corrosion inhibitors are also added to the solution toreduce the internal corrosion rates in the unit.

FORM 155.16-OM1


Solution Heat Exchanger:

A counterflow Solution To Solution heat exchanger.A component that exchanges heat between twostreams of Lithium Bromide solution. The hotter thesolution being supplied to the generators is, the lessheat that needs to be added, thus improving efficien-cy. Likewise, the cooler the solution is going to theAbsorber, the less heat that needs to be removed bythe cooling towers. Therefore, the heat exchanger pre-heats the solution going to the generator and cools thesolution going to the Absorber.

Solution Pump:

A hermetically sealed, centrifugal pump locatedunder the absorber. It receives diluted lithium bro-mide solution from the absorber shell and circulates itthrough a heat exchanger, then up to the generator.The discharge of this pump operates in a pressure thatis above atmospheric pressure. The pump is cooled bythe solution it is pumping.

Specific Gravity (S.G.):

The ratio of the mass a liquid to the mass of an equalvolume of distilled water at 39°F.

Steam Valve:

The capacity control valve which regulates theamount of steam to the unit (Steam units only).

Tube Sheet (End Sheet):

The book-ends of the mainshell. The tube sheets arelocated at each of the axial ends of the unit, where thetubes are rolled and waterboxes are mounted.

Tube Support:

A smaller gauge steel sheet, identical in tube hole lay-out to the tube sheet, but used internally to providesupport and rigidity for the bundle of tubes.

FIG. 25 – PRESSURE EQUIVALENTS

760

700

600

500

400

300

200

100

0

14.696

14

12

10

8

6

4

2

0

29.92

25

20

15

10

5

0

TORR(mmHg)

Atmosphere at 32˚F

Inches Hg (abs) PSIA

LD05113

ABSOLUTE UNITSMeasured From Absolute Zero

GAUGE UNITSMeasured From Atmospheric Pressure

ATMOSPHERICPRESSURE

(0 PSIG)(14.7 PSIA)

INCREASINGVACUUM

DECREASINGVACUUM

0 29.9214.7 76000

Absolute Zero Pressure or Perfect Vacuum

– PSIG

PSIGPSIA

TORR in Hg

– mm Hg

mm Hg

– in Hg

in Hg0

029.92760

14.7 (mm Hg) (Abs.)

FIG. 26 – VACUUM UNITS OF MEASUREMENT

LD05114


Vacuum:

When the pressure within a vessel is less than stan-dard atmospheric pressure.

The term “vacuum” usually refers to any pressurebelow atmospheric pressure The degree of vacuumcan be expressed in many ways, but most commonly,as in this manual, it is measured in inches of mercuryor millimeters of mercury.

One atmosphere is equal to 760 millimeters of mercu-ry absolute (Torr); 29.92 inches of mercury absolute;or 14.7 pounds per square inch absolute (see Fig. 25).

When vacuum is measured relative to atmosphericpressure and toward absolute zero, the negative sign(–) is used to indicate that it is a negative gauge pres-sure value. When vacuum is considered in the otherdirection, i.e., from absolute zero, the term absolute(or abs.) is used (See Figure 26).

From Figure 25, we can see that a pressure reading of300 Torr is the same as 11.8 in Hg (abs.) and 5.8 PSI(abs.).

Water Box:

A structure designed to contain the water both enter-ing and exiting the unit by using nozzles to restrict thewater into a contained area. The nozzle directs thewater into the waterbox where pressure builds up,forcing the water through the tubes. As the waterexits the tubes on the opposite end, it is restricted bythe waterbox on the other side of the tube bundle.Again, pressure builds up, and the water is eitherforced by a pass baffle back through another sectionof the tube bundle or directly out of the outlet nozzle.

YIA:

YORK IsoFlow™ Chiller

FR

OM

GE

NE

RA

TO

R




REFRIGERANT LIQUIDLOW TEMPERATURE

REFRIGERANT LIQUIDHIGH TEMPERATURE

TOWERWATER

CHILLED LIQUID

CONDENSERTOWER WATER

OUTLET

STEAM OR HOT WATERCONTROL VALVE

CHILLEDWATEROUTLET

CHILLEDWATERINLET

EVAPORATOR

ABSORBER

TOWERWATERINLET

2SOL

HOT WATER OR STEAM

PT1HP1

ABSOLUTEPRESSURE GAUGE

OILTRAP

PURGEPUMP

AU

TO

MA

TIC

DE

-CR

YS

TA

LL

IZA

TIO

N P

IPE

TO

GE

NE

RA

TO

R

SOLPUMP

REF.PUMP

1F

GENERATORGENERATOROUTLET

3F

SOL 3

* Orifices may differ between various models.

FORM 155.16-OM1 FORM 155.16-OM1

LD06022A

FIG. 27 – COMPLETE CYCLE DIAGRAM

YORK INTERNATIONAL 67 YORK INTERNATIONAL 67A

Randy L Schrum

67B YORK INTERNATIONAL

FORM 155.16-OM1

Tele: 800-861-1001www.york.com

Proud Sponsorof the 2002U.S. Olympic Team

36USC380

P.O. Box 1592, York, Pennsylvania USA 17405-1592 Subject to change without notice. Printed in USACopyright © by York International Corporation 2000 ALL RIGHTS RESERVED

Form 155.16-OM1 (1200)New Release

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