tecumseh refrigerant piping

7/31/2019 Tecumseh Refrigerant Piping

1/24

A LOOK AT SERVICE SAFETY

Installation and Replacement Information 85

5

INSTALLATION ANDREPLACEMENT

INFORMATIONI. Compressor Tube Connections . . . . . . . .86

II. Refrigerant Line Sizes . . . . . . . . . . . . . . .88

III. Refrigerant Line Pressure Drops . . . . . . .93

IV. Refrigerant Line Velocities . . . . . . . . . . . .98

V. Service Valves . . . . . . . . . . . . . . . . . . . .103

VI. Processing the System . . . . . . . . . . . . .103

VII. System Cleanup and Compressor

Replacement After Compressor

Failure. . . . . . . . . . . . . . . . . . . . . . . . . . .104

VIII. Replacing Compressors in Water-Utilizing Systems: Preventing

Explosions. . . . . . . . . . . . . . . . . . . . . . . .108

For more free Tecumseh literature please visit

www.HVACRinfo.com
http://www.hvacrinfo.com/http://www.hvacrinfo.com/


2/24

86 Chapter 5

I. Compressor Tube

Connections

Tecumseh Products Company supplies compressorsto hundreds of manufacturers requiring different

tubing sizes and arrangements. Because of this thesame compressor model may be foun d in th e field inmany suction and discharge tube variations, eachdepending upon the specific application in which itis installed.

Suction connections can usually be identified as thelargest diameter stub tube in the housing. If 2 stubshave the same outer diameter (OD), then the onewith th e heavier wall will be the suction conn ection.If both of the largest stub t ubes are the same O Dand wall thickness, then either can be used as thesuction connection. Whenever possible, suction

connections should be kept away from the hermeticterminal area so that condensation will not drip onherm etic terminals, causing corrosion.

The stub tube, not chosen for the suction connec-tion, may be u sed for p rocessing t he system.

Ident ification of compressor connections can usuallybe accomplished without difficulty; however, occa-sionally some question arises concerning oil coolertub es and process tub es.

Oil cooler tubes are found only in low temperaturerefrigeration models. These tubes connect to a coilor hairpin bend within the compressor oil sump.This coil or hairpin bend is not open inside thecomp ressor and its only fun ction is to cool the com-pressor sump oil. The oil cooler tubes are most gen-erally connected to a separated tubing circuit in theair cooled condenser.

Process tubes are installed in compressor housingsduring manufacture as an aid in factory dehydrationand charging.

Standard discharge tubing arrangements for Tecum-seh hermetic compressors are outlined below. Dis-charge tubes are generally in the same positionwithin any model family. Suction and process tubepositions may vary substantially.

Figure 5-1. Standard discharge tubing arrangements.

DischargeTube

DischargeTube

DischargeTube

DischargeTube

On some AE refrigerationmodels the terminal coverfaces the other way.

OptionalOil Cooler Tubes

AERefrigeration

AW-E AW-F

AEAir Conditioning


3/24



Figure 5-1. Standard discharge tubing arrangements - continued.

AKAir Conditioning

DischargeTube

DischargeTube

DischargeTube

DischargeTube

Discharge

Tube

DischargeTube

AJ

AH

AVAZ

AN

AG

AB

RK


4/24

88 Chapter 5

II. Refrigerant Line Sizes

A. R-12 and R-22 Refrigerant Line Sizes forRemote Systems Commercial

RefrigerationThe recommended suction line sizes are based pri-marily on the velocities necessary for good oilreturn. In most instances, the resulting pressuredrop will be acceptable for suction lines up to 100in length.

Refer to these installation considerations for goodoil return on comm ercial systems:

Slope horizontal suction line downwards in thedirection of th e comp ressor at least 1 /2 fall per

10 feet of line.

The setting of the refrigerant control device(expansion valve) should maintain a minimum

of superheat. This is typical of the usual direct

expansion evaporator s where the oil is return ed

by refrigerant vapor.

In the case of a flooded type evaporator (bot-tom feed, top suction h eader, large internal vol-

ume, low refrigerant/oil velocities), it is

necessary to maintain a liquid spillover into th e

suction line so as to return the oil with the liq-

uid refrigerant and to minimize oil trapping in

the evaporator. If because of the spillover, the

return gas is wet at the compressor, a suction

line accum ulator shou ld be installed adjacent to

the comp ressor.

O n systems with evaporato rs below -10F, theoil/refrigerant mixture reaches a maximum vis-

cosity when the refrigerant superheat is about

30F on R-22 and R-502 and when about 4 5F

to 60 F superheat on R -12 systems. O il may

return sluggishly in such cases because of the

high viscosity. Two solutions should be consid-

ered:

a. Reduce superheat.

b. Add a liquid to suction gas heat

exchanger close to the evaporator but

outside the refrigerated space.

O n m ultiple evaporator systems, prevent th e oil(and refrigerant) from collecting in an idle coil.If the evaporator coils are to operate indepen-

dently of each other, each should have its own

suction riser sized to t he coils capacity.

Insulate suction lines.

Tables 5-1 and 5-2 show recommended suction linesizes for installations where that line is horizontal ordown flow. In the event the suction line is up flow,use one stan dard size smaller. EXAM PLE: W here a7/8 diameter tube is recommended on that tablefor horizontal or down flow, the recommended size

for up flow would be 3/4 diameter.


5/24



Table 5-1: R-12 Refrigerant Line Sizes for Remote Systems Commercial Refrigeration

Cond. Unit

CAPACITY

(BTU/Hr.)

SUCTION LINE SIZESAT SYSTEM EVAPORATOR DESIGN TEMPERATURE Liquid Line

Size-40F -20F 0F +20F +40F

1200 5/8 1/2 3/8 3/8 3/8 1/4

2400 3/4 5/8 1/2 1/2 3/8 1/4

3600 7/8 3/4 5/8 1/2 1/2 1/4

4800 1 1/8 7/8 5/8 5/8 1/2 1/4

6000 1 1/8 7/8 3/4 5/8 1/2 1/4

7200 1 1/8 1 1/8 7/8 3/4 5/8 1/4

8400 1 3/8 1 1/8 7/8 3/4 5/8 3/8

9600 1 5/8 1 1/8 7/8 3/4 5/8 3/8

10800 1 5/8 1 1/8 1 1/8 7/8 5/8 3/8

12000 1 5/8 1 3/8 1 1/8 7/8 3/4 3/8

18000 2 1/8 1 5/8 1 1/8 1 1/8 7/8 3/8

24000 2 5/8 2 1/8 1 3/8 1 1/8 1 1/8 1/2

36000 3 1/8 2 1/8 1 5/8 1 3/8 1 1/8 1/2

48000 3 5/8 2 5/8 2 1/8 1 5/8 1 3/8 1/2

60000 3 5/8 2 5/8 2 5/8 1 5/8 1 3/8 1/2

72000 4 1/8 3 1/8 2 5/8 2 1/8 1 5/8 1/2


Cond. UnitCAPACITY(BTU/Hr.)

SUCTION LINE SIZES

AT SYSTEM EVAPORATOR DESIGN TEMPERATURE Liquid LineSize-40F -20F 0F +20F +40F

1200 3/8 3/8 3/8 3/8 1/4

2400 1/2 1/2 3/8 3/8 1/4

3600 5/8 1/2 1/2 3/8 1/4

4800 3/4 5/8 1/2 3/8 1/4

6000 3/4 5/8 1/2 1/2 1/4

7200 7/8 3/4 5/8 1/2 1/4

8400 7/8 3/4 5/8 1/2 1/4

9600 1 1/8 3/4 5/8 5/8 1/4

10800 1 1/8 7/8 3/4 5/8 3/8

12000 1 1/8 7/8 3/4 5/8 3/8

18000 1 3/8 1 1/8 7/8 3/4 3/8

24000 1 3/8 1 1/8 1 1/8 7/8 3/8

36000 1 5/8 1 3/8 1 3/8 1 1/8 1/2

48000 2 1/8 1 5/8 1 3/8 1 1/8 1/2

60000 2 1/8 2 1/8 1 5/8 1 3/8 1/2

72000 2 5/8 2 1/8 1 5/8 1 3/8 1/2


6/24

90 Chapter 5

B. R-22 Refrigerant Line Sizes for RemoteSystems Air Conditioning and HeatPumps

Condensers and evaporators should be designed andcircuited to maintain adequate velocity to prevent

oil trapping.

The tube sizes suggested below are for connectinglines of remote systems. The basis for selection is tomaintain adequate velocity which assures oil returnto the compressor, an acceptable pressure drop toassure compressor capacity and minimum tubingcost.

To assure ad equate oil retu rn, suction line velocitiesshould be minimum of 750 fpm for horizontal ordown flow and 1500 fpm for up flow. Gas velocitiesof 3000 fpm or more will create noise problems andshould be avoided.

W here a choice of line sizes is possible because of th eoverlap in the compressor capacity table, the largersized lines are suggested to minimize the systempressure d rop.

Consider th ese installation notes:

Suction line sizes (up flow) provide adequategas velocities to assure oil return to the com-

pressor and, therefore, remain constant in size

regardless of the vertical lift. Suction line trapsare not required. H orizontal suction lines are

sized larger to reduce pressure drop.

Suction line lengths in excess of 100 are notrecommended.

O n h eat pum p systems, the lines serving asboth a discharge line and suction line, should

be sized as a suction line.

Liquid line sizes are based on pressure dropsthat will not permit gas formation for horizon-

tal lengths up to 100.The recommendations shown in Table 5-3 are basedon the use of standard refrigeration grade tubingand do not include considerations for additionalpressure d rop due to elbows, valves, or reduced jointsizes.

Table 5-3: R-22 Refrigerant Line Sizes for Remote Systems Air Conditioning and Heat Pumps

SUCTION LINE OUTER DIAMETER

Nominal Compressor

Cooling Capacity(BTU/Hr.) Vertical Up

Flow

Vertical

Down Flowor

Horizontal

Liquid LineOuter

Diameter

Discharge Line Length &

Outer Diameter

25 50 1001500 FPM 2500 FPM

5700 9400 3/8 1/2 1/4 5/16 5/16 3/8

8000 13000 1/2 1/2 1/4 5/16 3/8 3/8

11200 18500 1/2 5/8 5/16 3/8 3/8 1/2

17000 30000 5/8 3/4 5/16 3/8 1/2 1/2

27000 44000 3/4 7/8 3/8 3/8 1/2 5/8

38000 51000 7/8 1 1/8 3/8 1/2 5/8 5/8

38000 67000 7/8 1 1/8 1/2 1/2 5/8 5/8

60000 102000 1 1/8 1 3/8 1/2 5/8 3/4 3/4

96000 156000 1 3/8 1 5/8 5/8 3/4 3/4 7/8

144000 228000 1 5/8 2 1/8 5/8 3/4 7/8 1 1/8


7/24



C. R-502 and R-134a Refrigerant Line Sizesfor Remote Systems CommercialRefrigeration

The selection of suction gas line sizes should beguided by th e following criteria:

Assurance of adequate velocity th us in suringoil return capability. (The tube size must be

limited to maintain velocities no less than 750

fpm for horizontal and down flow and no less

than 1 500 fpm for up flow.)

Assurance of acceptable pressure drop. (Thetube size should be limited to maintain veloci-

ties no greater than 1500 fpm for horizontal

and down flow and no greater than 2500 fpm

for up flow.

Assurance of satisfactory sound level. (Thetube size should be limited to maintain veloci-

ties no greater than 30 00 fpm .)

Assurance of minimum tubing cost. (Thetube size should be as small as possible while

satisfying the th ree points men tioned above.)

Tables 5-4 and 5-5 show recommended suction linesizes for installations where that line is horizontal ordown flow. In the event the suction line is up flow,use one stan dard size smaller. EXAM PLE: W here a7/8 diameter tube is recommended on that tablefor horizontal or down flow, the recommended sizefor up flow would be 3/4 diameter.


Cond. UnitCAPACITY

BTU/HR.

SUCTION LINE SIZES

AT SYSTEMS EVAPORATOR DESIGN TEMPERATURE Liquid Line

Size-40F -20F 0F +20F +40F

1200 1/2 3/8 3/8 3/8 3/8 1/4

2400 5/8 1/2 1/2 3/8 3/8 1/4

3600 3/4 5/8 1/2 1/2 3/8 1/4

4800 7/8 3/4 5/8 1/2 1/2 1/4

6000 1 1/8 7/8 5/8 5/8 1/2 1/4

7200 1 1/8 7/8 3/4 5/8 1/2 1/4

8400 1 1/8 7/8 3/4 5/8 1/2 1/4

9600 1 1/8 1 1/8 7/8 3/4 5/8 1/4

10800 1 3/8 1 1/8 7/8 3/4 5/8 3/8

12000 1 3/8 1 1/8 7/8 3/4 5/8 3/8

18000 1 5/8 1 3/8 1 1/8 7/8 3/4 3/8

24000 2 1/8 1 5/8 1 3/8 1 1/8 7/8 3/8

36000 2 5/8 2 1/8 1 5/8 1 3/8 1 1/8 1/2

48000 2 5/8 2 1/8 1 5/8 1 3/8 1 1/8 1/2

60000 3 1/8 2 5/8 2 1/8 1 5/8 1 3/8 1/2

72000 3 5/8 2 5/8 2 1/8 1 5/8 1 3/8 1/2


8/24

92 Chapter 5

Table 5-5: R-134a Refrigerant Line Sizes for Remote Systems Commercial Refrigeration

Cond. UnitCAPACITY

(BTU/Hr.)

SUCTION LINE SIZES

AT SYSTEMS EVAPORATOR DESIGN TEMPERATURE Liquid Line

Size-40F -20F 0F +20F +40F

1200 5/8 1/2 3/8 3/8 3/8 1/4

2400 3/4 5/8 1/2 1/2 3/8 1/4

3600 7/8 3/4 5/8 1/2 1/2 1/4

4800 1 1/8 7/8 3/4 5/8 1/2 1/4

6000 1 1/8 7/8 3/4 5/8 1/2 1/4

7200 1 3/8 1 1/8 7/8 3/4 5/8 1/4

8400 1 3/8 1 1/8 7/8 3/4 5/8 3/8

9600 1 5/8 1 1/8 7/8 3/4 5/8 3/8

10800 1 5/8 1 3/8 1 1/8 7/8 3/4 3/8

12000 1 5/8 1 3/8 1 1/8 7/8 3/4 3/8

18000 2 1/8 1 5/8 1 3/8 1 1/8 7/8 3/8

24000 2 5/8 2 1/8 1 3/8 1 3/8 1 1/8 1/2

36000 3 1/8 2 1/8 2 1/8 1 3/8 1 1/8 1/2

48000 3 5/8 2 5/8 2 1/8 1 5/8 1 3/8 1/2

60000 3 5/8 3 1/8 2 5/8 2 1/8 1 5/8 1/2

72000 4 1/8 3 1/8 2 5/8 2 1/8 1 5/8 1/2


9/24



III. Refrigerant Line Pressure Drops

Figure 5-2. Refrigerant line pressure drops for Freon 12 refrigerant (reprinted by permission of DuPontFluorochemicals).

.

2

.

3

.

4

.

6

.

8

2 3 4 6 8 1

0

2

0

3

0

4

0

6

0

8

0

1

00

2000

3000

4000

6000

8000

10

,000

BTU's Per HR

0.

2

0.

2

0.

3

0.

4

0.

6

0.

8 1 2 3 4 5 6 810

20

30

40

50

0.

3

0.

4

0.

6

0.

8 1 2 3 4 5 6 810

20

30

40

50

EXAMPLE:

5.5 Tons at -4 0C Evap. 85F Cond.

3 1/8" Suction Line Pressure Drop = 0.155 p.s.i./100 ft.3/4" Liquid Line Pressure Drop = 1.0 p.s.i./100 ft.

At 120F Condenser

At 100F Condenser

At 80F Condenser

61/8

"

51/8

"

41/8

"

35/8

"

31/8

"

21/8

"

15/8

"

11/8

"

7/8"

3/4"

5/8"

1/2"

3/8"

-60

F

Eva

pora

torT

empe

ratu

re

-40F

40F

Dis

char

geL

ines

80

F

Con

dens

er

100F

Con

dens

er

120

FC

onde

nser

Liqu

idL

ine

-20

F

20F

0F

13/8

"O.D.TypeLCo

pper

Tubing

25/8

"

Tons of Refrigeration

Pressure Drop In Lbs. Per Sq. In. Per 100 Ft.

NOTE: Pressure drops do notallow for pulsating flow. Ifflow is pulsating, use nextlarger pipe size. Liquidline determined at 0Fevap. & 80F cond.Discharge lines at 0Fevap. Other conditions donot appreciably changeresult. Vapor evap. outlet

assumed to be at 65F.


10/24

94 Chapter 5

Figure 5-3. Refrigerant line pressure drops for Freon 22 refrigerant (reprinted by permission of DuPont

Fluorochemicals).

0.

2

0.

3

0.

4

0.

6

0.

8

1 2 3 4 6 8 10

20

30

40

60

80

100

2000

3000

4000

6000

8000

10

,000

BTU's Per HR

0.

2

0.2 0.3 0.4 0.6 0.8 1 2 3 4 5 8 10 20 30 40 506

0.

3

0.

4

0.

6

0.

8 1 2 3 4 5 6 810

20

30

40

50

At 80F Condenser

At 100F Condenser

At 120F Condenser

61/8

"

51/8

"

41/8

"

35/8

"

25/8"

15/8

"

11/8

"

7/8"

3/4"

5/8"

1/2"

3/8"

-60FE

vaporator

Temperature

-40F

13/8

"O.D.TypeL

Copper

Tubing

31/8

"

21/8

"



EXAMPLE:

5.5 Tons at -40F Evap. 85F Cond.

2 5/8" Suction Line Pressure Drop = 0.18 p.s.i./100 ft.

5/8" Liquid Line Pressure Drop = 1.7 p.s.i./100ft.

-20F

20F

40F

Dischargelin

es80F

Condenser

100F

Condenser

120FC

ondenser

Liquid

Line

0F

NOTE: Pressure drops do not allowfor pulsating flow. If flow ispulsating, use next largerpipe size. Liquid linedetermined at 0F evap. &80F cond. Discharge linesat 0F evap. Otherconditions do not

appreciably change result.Vapor evap. outlet assumedto be at 65F.


11/24



Figure 5-4. Refrigerant line pressure drops for Freon 502 refrigerant (reprinted by permission of DuPont

0.2

0.3

0.4

0.6

0.8

1 2 3 4 6 8 10

20

30

40

60

80

100

200

0

300

0

400

0

600

0

800

0

10,00

0

BTU's Per HR

0.2

0.2

0.3

0.4

0.6

0.8 1 2 3 4 6 81

020

30

40

50

2 3 4 5 6 810 20 30 40500.3 0.4 0.6 0.8 1

At 80F CondenserAt 100F Condenser

At 120F Condenser

71/8

"

61/8

"

51/8

"

41/8

"

35/8

"

31/8

"

25/8

"

21/8

"

15/8

"

13/8

"

11/8

"

7/8"

3/4"

1/2"

3/8"

5/8"O

.D.TypeL

Copp

erTubin

g

-60

FEva

pora

torT

empe

ratu

re

-40

F



EXAMPLE:


Choose 2 5/8" Suction Line Pressure Drop = 0.3

Choose 3/4" Liquid Line Pressure Drop = 1.7

-20

F

20F

40F

Disch

arge

Lin

e

Liqu

idL

ine0

F

NOTE: Pressure drops do not allow forpulsating flow. If flow is pulsating,

use next larger pipe size.


12/24

96 Chapter 5

Figure 5-5. Refrigerant line pressure drops for HP62 (404A) refrigerant (reprinted by permission of DuPont

Fluorochemeicals).

0.1

0.2

0.3

0.4

0.6

0.8

1 2 3 4 6 8 10

20

30

40

60

80

100

200

300

400

600

800

1000

0.0

10.4

0.6

0.8 1 2 3 4 6 81

0

0.0

80.1

0.2

0.3

0.0

2

0.0

2

0.0

3

0.0

4

0.0

6

0.0

80.1

0.2

0.3

0.4

0.6

0.8 1 2 3 4 6 81

0

0.0

3

0.0

4

0.0

6

At 30C Condenser

At 40C Condenser

At 50C Condenser

61/8

"O.D.TypeLCo

pper

Tub

ing

51/8

"

41/8

"

35/8

"

31/8

"

25/8

"

21/8"

15/8

"

13/8

"

11/8

"

7/8"

3/4"

5/8"

1/2"

3/8"

-50C

Evaporato

rTe

mpe

ratu

res

-40C

-20C

0C

-30C

-10C

10C

Dis

charge

Lin

es

Lines

Lin

es

Pressure Drop In Kpai Per Meter


EXAMPLE:

15 kW at -40C Evap., 40C Cond.

2 1/8" Suction Line Pressure Drop = 0.11kPa/m5/8" Liquid Line Pressure Drop = 0.47 kPa/m

NOTE: Pressure drops do notallow for pulsating flow.If flow is pulsating, usenext larger pipe size.Liquid line and discharge

lines determined at -20Cevap. and 30C cond.Other conditions do notappreciably changeresult. Vapor at evap.

outlet assumed to be at 20C.


13/24



Figure 5-6. Refrigerant line pressure drops for HFC-134a refrigerant (reprinted by permission of DuPontFluorochemicals).

0.2

0.3

0.4

0.5

0.60.8 1 2 3 4 6 81

020

30

40

0.1

0.2

0.4

0.6

1 2 4 6 10

20

30

40

60

100

0.1

0.2

0.3

0.4

0.6

0.8 1 2 3 6 81

020

30

40

60

80

100


At 120F Condenser

61/8

"O.D.TypeL

Copp

erTu

bing

-60F

EvaporatorTe

mperatu

re

-40F

-20F

20F

40F

Dis

charg

eL

ines

Liquid

Lin

es

0F

51/8

"

41/8

"

35/8

"

31/8

"

25/8

"

21/8

"

15/8

"

13/8

"

11/8

"

7/8"

3/4"

5/8"

1/2"

3/8"

Pressure Drop In Psi Per 100 Ft.


EXAMPLE:

25 Tons at -40F Evap. and 100F Cond.

2 5/8" Suction Line

Pressure Drop = 5.5 p.s.i./100 ft.

1 1/8" Liquid Line

Pressure Drop = 1.6 p.s.i./100 ft.

NOTE: Pressure drops do notallow for pulsating flow.If flow is pulsating, usenext larger pipe size.Liquid line and discharge

lines determined at 0Fevap. and 80F cond.Other conditions do notappreciably changeresult. Vapor at evap.

outlet assumed to be at 65F.


14/24

98 Chapter 5

IV. Refrigerant Line Velocities

Figure 5-7. Refrigerant line velocities for Freon 12 refrigerant (reprinted by permission of DuPont

Fluorochemicals).

0.

1

0.

2

2000

3000

4000

6000

8000

10

,000

BTU's Per HR

0.

4

0.

6

1 2 4 6 10

20

40

60

100

15

20

30

40

50

60

70

80

100

150

200

300

400

500

600

1000

1500

2000

3000

4000

5000

6000

7000

8000

10

,000

800

700

15

20

30

40

50

60

70

80

100

150

200

300

400

500

600

1000

1500

2000

3000

4000

5000

6000

7000

8000

10

,000

800

700

At 80F Condenser

EXAMPLE:

5.5 Tons at -4 0F Evap. 85F Cond.

3 1/8" Suction Line Velocity = 1916 ft./min.3/4" Liquid Line Velocity = 94 ft./min.

At 100F Condenser

At 120F Condenser

61/8

"

-60FEvap

orator

Temperature

-40F

-20F

0F

20F

40F

80F

Condenser

51/8

"

41/8

"

35/8

"

13/8

"

3/4"

5/8"

31/8

"

25/8

"

21/8

"

15/8

"

11/8

"

7/8"

O.D.TypeLCo

pper

Tubing

1/2"

3/8"


Velocity In Feet/Minute

100F

Condenser

LiquidLine

Discha

rgeLines12

0F

Conden

ser

NOTE: Liquid line determined at0F evap. and 80F cond.Discharge lines at 0Fevap. Net refrigeration for"Freon" 12 includessuction gas at 65F.


15/24



Figure 5-8. Refrigerant line velocities for Freon 22 refrigerant (reprinted by permission of DuPont Fluorochemicals).

0.

1

0.

2

0.

4

0.

6

1 2 4 6 10

20

40

60

100

200

0

300

0

400

0

600

0

800

0

10

,00

0

BTU's Per HR

15

15

20

30

40

60

80

100

150

200

300

400

600

800

1000

1500

2000

3000

4000

6000

8000

10

,000

20

30

40

60

80

100

150

200

300

400

600

800

1000

1500

2000

3000

4000

6000

8000

10

,000


At 120F Condenser

51/8

"

41/8

"

-60FEv

aporatorTe

mperatu

re

Discha

rgelin

es80F

Cond

enser

-40F

-20F

20F

40F

Liquid

Line

100F

Cond

enser

120F

Conden

ser

0F

35/8

"

31/8

"

25/8

"

21/8

"

15/8

"

13/8

"

11/8

"

7/8"O

.D.TypeLCo

pper

Tubing

5/8"

1/2"

3/8"

3/4"


Velocity, Feet/M inute

EXAMPLE:



NOTE: Liquid line determinedat 0F evap. and 80Fcond. Discharge linesat 0F evap. Netrefrigeration for "Freon"22 includes suction gasat 65F.


16/24

100 Chapter 5

Figure 5-9. Refrigerant line velocities for Freon 502 refrigerant (reprinted by permission of DuPont

Fluorochemicals).

0.1

0.2

0.4

0.6

1 2 4 6 10

20

40

60

100

2000

3000

4000

6000

8000

10,0

00

BTU's Per HR

15

20

30

40

50

60

80

100

150

200

300

400

500

600

800

1000

1500

2000

3000

4000

5000

6000

8000

10,0

00

15

20

30

40

50

60

80

100

150

200

300

400

500

600

800

1000

1500

2000

3000

4000

5000

6000

8000

10,0

00


At 120F Condenser

61/8

"

15/8

"

13/8

"

11/8

"

7/8"

3/4"

5/8"

1/2"

3/8"

51/8

"

41/8

"

35/8

"

31/8

"

25/8

"

21/8

"

-60FEv

aporator

Temperature

-40F

-20F

0F

20F

40F

Discha

rgeLines80

FConde

nser

100F

Conden

ser

120F

Cond

enser

Liquid

Line


Velocity, Feet/Minute

EXAMPLE:



NOTE: Liquid line determined

at 0F evap. and 80Fcond. Discharge linesat 0F evap. Netrefrigeration for "Freon"502 includes suction gas

at 65F.


17/24



Figure 5-10. Refrigerant line velocities for HP62 (404A) refrigerant (reprinted by permission of DuPont

Fluorochemicals).

0.

1

0.

2

0.

3

0.

4

0.

6

0.

8

1 2 3 4 6 8 10

20

30

40

60

80

100

200

300

400

600

800

100

0.

1

0.

2

0.

3

0.

4

0.

6

0.

8 1 2 3 4 6 810

20

30

40

60

80

100

0.

2

0.

3

0.

4

0.

6

0.

8 1 2 3 4 6 810

20

30

40

60

80

100

At 30C Condenser

At 40C Condenser

At 50C Condenser

61

/8"O

.D.Typ

eLC

opperTu

bing

51

/8"

41

/8"

35

/8"

31

/8"

25

/8"

7/8"

3/4"

5/8"

3/8"1/

2"

21

/8"

15

/8"

11

/8"

13

/8"

-50C

EvaporatorTe

mperatu

res

-40C

-30

C

-20C

0C-1

0C

10C

Dis

charg

eL

ines

Liquid

Lin

es

Velocity In M/S

Kilowatts of Refrigeration

EXAMPLE:


2 1/8" Suction Line Velocity = 38 m/s1 3/8" Liquid Line Velocity = 0.55 m/s

NOTE: Liquid line and discharge lines determined at -20C evap.and 30C cond. Other conditions do not appreciably changeresult. Net refrigeration for HP-62 includes suction gas at 20 C.


18/24

102 Chapter 5

Figure 5-11. Refrigerant line velocities for HFC-134a refrigerant (reprinted by permission of DuPont Fluorochemicals).

0.1

0.2

0.3

0.4

0.5

0.6

1 2 3 4 6 8 10

20

30

40

60

80

100

200

300

400

600

800

1000

0.2

0.1

0.2

0.3

0.4

0.6

0.8 1 2 3 4 6 81

020

30

40

60

80

100

0.3

0.4

0.6

0.8 1 2 3 4 6 81

020

30

40

60

80

100

At 30C Condenser

EXAMPLE:


3 1/8" Suction Line Velocity = 18 m/s1 3/8" Liquid Line Velocity = 0.37 m/s

NOTE: Liquid line determined at -20C evap. and 30C cond.

Discharge lines at -20C evap. Other conditions do not

appreciably change result. Net refrigeration forHFC-134a includes suction gas at 20C.

At 40C Condenser

At 50C Condenser

61/

8"O

.D.Typ

eLCoppe

rTu

bin

g

51/

8"

41/

8"

31/

8"

21/

8"3

5/8"

25/

8"

15/

8"

13/

8"

11/

8"

7/8"

3/4"

5/8"

1/2"

3/8"

-50C

EvaporatorTe

mperatu

res

-40C

-30C

-20

C

-10C

0C

10C

-40

C

Condenser

-50

C

Condenser

Liq

uid

Line

s

Dis

charg

eLin

es-

30C

Cond

ens

er

Kilowatts of Refrigeration

Velocity In M/S


19/24



V. Service Valves

As shipped with the compressors, the rotolock ser-vice valves have a small plastic dust plug inside thethreaded end. Be sure to remove this plug before

installing.Service valves on Tecumseh systems are frontseated by turning the valve stem clockwise. Thiscloses the valve and opens the gauge por t.

Turning the stem counter-clockwise back seats thevalve and t hu s opens th e system and closes the gaugeport.

If present, t he valve port t o th e system cont rol (highpressure cutout, low pressure control, fan controletc.) is always open regardless of the position of thevalve stem.

If it is desired to operate th e system with the servicegauge operating, it is necessary to crack the valvefrom its back seated position for the gauges to per-form. Before removing the gauges, close the gaugeport by return ing th e valves to t heir fully open posi-tion (back seated).

Remember to check the packing gland nut (ifpresent ) on the stem for snugness before leaving t he

job . Install t he cover n ut over th e valve stem as a sec-ond ary safeguard against leaks at th e stem.

VI. Processing the System

The performance and longevity of a refrigerationsystem is stron gly influen ced by h ow th e system wasprocessed, that is, how the system was prepared foroperation at the time of installation. The procedureis:

1. O n split systems, install the liquid and suction

line. See Refrigerant Line Sizes on pages 88-

92 for recommended line sizes. A properly

sized suction line accumulator is recom-

mended . See Accum ulator Selection D ata onpage 118 for accumulator sizing. Insulate the

suction line to reduce heat exchange and

excessive return gas temperatures to the com-

pressor.

2. To prevent oxidation and scale forming inside

the tubes, it is good practice to flow dry nitro-

gen through the tubing during the soldering

operations. A light flow of abou t 1/ 4 cub ic feet

per minu te is sufficient.

3. Install a filter in th e liquid line imm ediately

ahead of th e capillary tube or expansion valve.

A liquid line drier should also be installed.

4. A suction line filter/drier is recomm ended to

prot ect the comp ressor. A suction accumu lator

must be installed on those systems having

defrost cycles (heat pumps, low temperature

refrigeration) or the likelihood of periodic

floodbacks (bulk milk coolers, ice machines).

See Accum ulator Selection D ata on page 118

for accumu lator sizing.

5. Pressure test the system for leaks using the

safety precautions outlined in System Flush-

ing, Purging, and Pressure Testing for Leaks

on pages 4-5. D o not p ressurize the system

beyond 150 PSIG fi eld leak test pr essure.

6. Use a vacuum pum p (not a compressor) to

draw a vacuum of 1000 microns or less from

both sides of the system. It is a waste of time to

attempt to draw a vacuum on a system with

the pump connected only to the low side.

Entry must be made directly into the high

pressure side to properly evacuate that p ort ion

of the system. Use a good electronic gauge to

measure the vacuum. An accurate reading can-

not be made with a refrigeration gauge.

Remember 29 of mercury as read on a com-

pound gauge equals 23,368 microns of vac-

uum.

WARNING! Never use a compressor to

evacuate a system. Instead, use a high vac-

uum pump specifically designed for that pur-

pose.

Never start the compressor while it is under

deep vacuum. Always break a vacuum with

refrigerant charge before energizing the

compressor.

Failure to follow these instructions can dam-

age the hermetic terminal and may result in

terminal venting. As always, to reduce the

risk of serious injury or death from fire due

to terminal venting, never energize the com-

pressor unless the protective terminal cover

is securely fastened.


20/24

104 Chapter 5

7. If a suction line accum ulator is present, charge

into the accumulator to prevent liquid refrig-

erant from reaching the compressor. If this is

not possible, then break the vacuum by allow-

ing refrigerant vapor to enter the low side at

the suction service valve. When the system

pressure reaches 60 psig for R-22 (70 psig for

R-502, 35 psig for R-12), start the compressor

and cont inue charging at rate not m ore than 5

pounds per minutes for the larger systems and

somewhat less for smaller systems. Follow the

safety precautions outlined in System Charg-

ing on p ages 5-6.

8. Ch eck fans and blowers for correct direction

of rotation, belt tension, and proper air flow

(CFM).

9. With th e protective terminal cover securely

fastened, run the compressor and allow the

system pressures and temperatures to stabilize.

Systems vary in their operating characteristics

bu t generally these approximations will apply:

10. Before leaving the job ru n the system for

awhile. Listen for abnormal noises. Feel the

bottom crankcase housing and d etermine th at

it is warm. Is the compressor upper housing

sweating indicating that liquid refrigerant is

reaching the compressor? Is the return gas

temperature at the compressor 65F or less

and not more than 80F? Recheck pressures,

amps, fan motors, belts, CFM, etc.

VII. System Cleanup and

Compressor Replacement

After Compressor Failure

Once you determine that a compressor needs to be

replaced you must then determine whether the sys-tem has been contaminated. C omp ressor m otor fail-ure can lead to such contamination. (Whilecomp ressor motor failure is sometimes referred to asmotor burnout, it does not mean that a fire actu-ally occurs inside a hermetic compressor.) Evensmall amounts of contamination must be removedfrom the system to avoid damaging the replacementcompressor. Therefore, it is important to thoroughlyclean a refrigeration/air conditioning system if sys-tem con tamination is present.

If a compressor motor failure has occurred,refrigerant or mixtures of refrigerant and oil inthe system can be acidic and cause chemicalburns. As always, to avoid injury, wear appro-priate protective eyewear, gloves and clothingwhen servicing an air conditioning or refrigera-tion system. If refrigerant or mixtures of refrig-erant and oil come in contact with skin or eyes,flush the exposed area with water and get medi-cal attention immediately.

The following outlines a process for compressorreplacement and system clean-up for a systemequipp ed with a Tecum seh comp ressor. You shouldrefer to the original equipment manufacturers(O EM ) service information.

A. Determine Extent of SystemContamination

Following the precautions in Refrigerants andOther Chemicals and Compressor Removal onpage 4, remove the compressor.

Use the following guidelines to determine whethercontamination, if any, is limited to the compressoror extends to t he system.

If the discharge line shows no evidence of contami-nation and t he suction stub is clean or has only lightcarbon deposits, then the contaminants are limitedto th e compressor hou sing (Com pressor H ousing

Table 5-6: Pressure and TemperatureStabilization

Pressure Temperature

Saturated Head

Pressure

Ambient temperature F + 25F for

air cooled condenser.

Water cooled Discharge water F + 10F

Saturated evaporator pressure

Air Conditioning Discharge air F - 20F

Medium

TemperatureProduct temperature -10F to -12F

Low Temperature Product temperature -6to -8F

! WARNING


21/24



Contamination). A single installation of liquid and

suction line filter-driers shou ld cleanup t he system.

If, however, the discharge line or the suction line

shows evidence of contamination, the compressor

was running at the time of the motor failure and

contaminants were pumped throughout the system

(System Con tamination). If System Con tamination

has occurred, several changes of the liquid and suc-

tion line filter-driers will be needed to cleanup the

system. In addition, the expansion device will need

to be replaced. If the system is a heat pump, t he four

way valve should be replaced.

B. Install Replacement Compressor and

Components1. Install the replacement compressor with new

external electrical components (capacitors,

relay, overload, etc., where applicable). Check

the contacts of the starting control or contac-

tor.

2. Install an oversized liquid line filter-drier.

3. Install a generously sized suction line filter-

drier imm ediately upstream of th e compr essor.

The drier when permanently installed in aclean system, or as initially installed in a dirty

system, must have a pressure drop not more

than that of Table 5-3. Pressure taps must be

supplied imm ediately before and after the suc-

tion filter-drier to permit the pressure drop to

be measured.

If a suction line accumulator is present and

System Contamination has occurred, it must

be thoroughly flushed to remove any trapped

sludge and thus prevent it from plugging the

oil return hole. The filter-drier should be

installed upstream of the accumulator and the

compressor.

In the case of Compressor Housing Contami-

nation, the filter-drier should be installed

between the compressor and the suction line

accumulator.

Rubber refrigeration hoses are not satisfactory

for temporarily hooking up th e suction line fil-

ter-drier to the system since the acid quickly

breaks down the rubber and plastic.

4. Follow the precautions in System Flushing,

Purging, and Pressure Testing for Leaks on

pages 4-5, to purge the system and pressure

test for leaks.

C. Evacuate the System

Evacuate the system to less than 1000 microns,

using a good vacuum pum p (not a compressor) and

an accurate high vacuum gauge. O perate the pu mp

at 10 00 microns, or less, for several hou rs to be sure

the vacuum is maintained.

An alternate method of removing moisture and non -

cond ensables from the system is:

1. Evacuate the system to 29 inches vacuum.

Break vacuum with refrigerant to be used for

final charging of system and vapor charge to

35-50 pounds gauge pressure. Leave vapor

charge in system for a minimum of five min-

utes. Reduce pressure to 0 gauge p ressure.

2 . Repeat step 1.

3. Evacuate system to 29 inches vacuum. Ch arge

system with the specified kind and quantity of

refrigerant.

WARNING! Never use a compressor to evacuate

a system. Instead, use a high vacuum pump specif-

ically designed for that purpose.

Never start the compressor while it is under deep

vacuum. Always break a vacuum with refrigerantcharge before energizing the compressor.

Failure to follow these instructions can damage

the hermetic terminal and may result in terminal

venting. As always, to reduce the risk of serious

injury or death from fire due to terminal venting,

never energize the compressor unless the protec-

tive terminal cover is securely fastened.


22/24

106 Chapter 5

D. Charge the System and Check thePressure Drop

Charge the system and place in operation. Followthe safety precautions outlined in System Charg-ing on pages 5-6. Immediately after startup, checkthe pressure drop across the suction line filter-drier.This will serve two purposes:

Verify that the drier selection was correct; thatis, large enough.

Serve as a base point to wh ich subsequent pr es-sure checks can be compared.

Because the permissible pressure drop across thedrier is relatively small, it is suggested that a differ-ential pressure gauge be used for the measuremen t.

E. Measure the Pressure Drop

After the system has been operating for an hour orso, measure th e pressure d rop across the suction linefilter-drier.

In th e case of Com pressor Hou sing Con tamination,little change should be noted. The pressure dropwill, in m ost instances, be below t hat t olerable for apermanent installation (see Table 5-3).

On the other hand, where System Contaminationoccurred, an increased pressure drop will be mea-sured. Change the suction filter-drier an d the liquidline filter-drier whenever the pressure dropapproaches or exceeds that allowed for temporaryoperation during cleanup (see Table 5-4).

Keep changing both the suction and liquid line fil-ter-driers until th e pressure d rop stabilizes at a figureequal to or below that permitted for permanentoperation in a system (see Table 5-3). At t his point ,it is the service persons option as to whether to leavethe suction drier in the system or remove it from

operation.

If the system is to be opened to permit the perma-nent removal of the suction filter-drier then the liq-uid line filter-drier should be changed once more.

Table 5-3: Suggested Maximum Pressure Drop (PSI) for Permanent Suction Filter-Drier Installation

Application Air Cond. High Medium Low Low

Evaporator Range, F +55 to +32 +55 to +20 +30 to -10 +10 to -20 -20 to -40

R-12 2 2 1 1/2 1/2 1/2

R-22 3 3 2 1 1/2

R-502 3 3 2 1 1/2

Table 5-4: Suggested Maximum Pressure Drop (PSI) for Temporary Suction Filter-Drier InstallationDuring Cleanup

Application Air Cond. High Medium Low Low

Evaporator Range, F +55 to +32 +55 to +20 +30 to -10 +10 to -20 -20 to -40

R-12 9 9 6 2 3/4

R-22 15 15 9 3 1 1/2

R-502 15 15 9 3 1 1/2


23/24



F. Test for Acidity If Multiple Motor FailuresHave Occurred

If the system has suffered m ultiple motor failures, itis advisable that the oil of the replacement be testedafter Section E and judged acid free before the sys-tem is considered satisfactorily cleaned. An oil sam-ple may be taken from a hermetic system if at thetime the replacement com pressor was installed an oiltrap is installed in th e suction line (see Figure 5-12).W hen the trapped oil level appears in the sight glass(less than an ounce is needed) the oil may be slowlytransferred to the b eaker of th e acid t est kit as avail-able from several manufacturers. A reading of lessthan 0.05 acid nu mb er is an ind ication that the sys-

tem is free of acid. A reading of higher than 0.05means continued cleaning is required. Return to B2on page 105.

G. Monitor the System

The above procedure for the cleanup of hermeticsystems after motor failure through the use of suc-tion line filter-drier will prove satisfactory in mostinstancesprov id ed the system is monitored and keptclean by repeated drier changes, if such are needed.T he failure to follow th ese minimum cleanup recom-mendations will result in an excessive risk of repeatmotor failure.

Figure 5-12. Method of obtaining oil sample on hermetic system. After satisfactory oil test,Schrader valve may be capped and the oil sampler taken to next job.

Schrader Valve Vertically Downward

Female Schrader Valve Connection

1/2" Liquid Sight Glass

1/2" Shut Off Valve

2"

Minimum

At Least 6 Diameters

Suction Line


24/24

VIII. Replacing Compressors in

Water-Utilizing Systems:

Preventing Explosions

In certain water-utilizing refrigeration systems,water can leak into the refrigerant side of th e system.This can lead to an explosion of system compo-nents, including b ut not limited to, the comp ressor.If such an explosion occurs, the resulting blast cankill or seriously injure anyone in the vicinity.

Water-utilizing systems that have single-wall heatexchangers may present a risk of explosion. Suchsystems may include:

water source heat pump/air conditioning sys-tems, and

water cooling systems, such as icemakers, watercoolers, and juice dispensers.

Water-utilizing systems that have single-wall heatexchangers present a risk of explosion unless theyhave either:

a high pressure cut-out which interrupts powerto ALL leads to the com pressor or

an external p ressure relief valve.

Before replacing a compressor in a water-utilizingsystem, read and follow Prevention of Water-Utiliz-ing System Explosions on pages 6-7.

tecumseh refrigerant piping

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