equipment room design

© American Standard Inc. 1997 © American Standard Inc. 1997

The Trane CompanyLa Crosse, Wisconsin

Refrigeration System

Equipment Room DesignRefrigeration System

Equipment Room Design


ANSI/ASHRAE Standards

Standard 34-1992 …

“Number Designation And Safety Classification Of Refrigerants”

Standard 15-1994 …

“Safety Code For Mechanical Refrigeration”


“Number Designation AndSafety Classification Of Refrigerants”

Purpose? To establish a …

“… simple means of referring to common refrigerants instead of using the chemical name, formula, or trade name.”

“… uniform system for assigning reference numbers and safety classifications to refrigerants.”

ANSI/ASHRAE Standards …

Standard 34-1992


ASHRAE Standard 34-1992 …

Refrigerant Safety Classifications

Group A3

Group A2

Group A1

Group B3

Group B2

Group B1

higherflammability

lowerflammability

no flamepropagation

lower toxicity higher toxicity



Refrigerant/Blend Data

Refrigerant Chemical Name OrComposition (% By Weight)

Methane Series

CFC (or R) –11 Trichlorofluoromethane 75°F A1 1.6 4,000CFC (or R) –12 Dichlorodifluoromethane –22°F A1 12.0 40,000HCFC (or R) –22 Chlorodifluoromethane –41°F A1 9.4 42,000

Ethane Series

CFC (or R) –113 1,1,2–Trichlorotrifluoroethane 118°F A1 1.9 4,000HCFC (or R) –123 2,2–Dichloro–1,1,1–Trifluoroethane 81°F B1 0.4 1,000HFC (or R) –134a 1,1,1,2–Tetrafluoroethane –15°F A1 16.0 60,000HFC (or R) –152a 1,1–Difluoroethane –13°F A2 1.2 7,000

Azeotropes

R–500 R–12 (73.8) / R–152a (26.2) –27°F A1 12.0 47,000R–502 R–22 (48.8) / R–115 (51.2) –49°F A1 19.0 65,000

NormalBoilingPoint

SafetyGroup

Lbs/1000cu ft

PPMByVol

Refrig Qty Per Occupied Space



Standard 15-1994

Purpose? “… to specify safe design, construction, installation,

and operation of refrigerating systems.”

Scope? “This code established safeguards for life, limb, health,

and property and prescribes safety standards.”

“Safety Code ForMechanical Refrigeration”



Standard 15-1994

It applies to …

“ … mechanical refrigerating systems and heat pumps used in the occupancies defined in Section 4 and installed subsequently to adoption of this code”




Standard 15-1994

It also applies to …

“… parts or components added after adoption of this code, or a change to a refrigerant of a different number designation after adoption of this code”




Standard 15-1994

Finally, it applies to …

“… parts or components replaced after adoption of this code only if they are not identical in function”




Standard 15-1994

Provides classification criteria for …

Safety group

Occupancy type

Refrigerating system “probability”




Safety Group Classification

Standard 34’s refrigerant safety classifications

Group A3

Group A2

Group A1

Group B3

Group B2

Group B1

higherflammability

lowerflammability

no flamepropagation

lower toxicity higher toxicity



Standard 15-1994


Safety group

Occupancy type





Occupancy Classification

Institutional Occupants can’t readily leave without help

Public assembly Where large numbers of occupants can’t vacate quickly

Residential Occupants have complete, independent living facilities

Industrial Occupancy is restricted only to authorized personnel



Occupancy Classification

Commercial Occupants transact business, receive personal

services, or purchase food or other goods

Large mercantile Premises where more than 100 people congregate to

purchase personal merchandise

Mixed Two or more occupancies share the same building



Standard 15-1994


Safety group

Occupancy type





Refrigerating System Probability

High Probability

Low Probability

SystemDesignation

Cooling Or Heating Source

Air Or SubstanceTo Be Cooled, Heated

Direct

IndirectOpen Spray

Double IndirectOpen Spray

IndirectClosed

IndirectVented Closed


ASHRAE Standard 15-1994…

Refrigerant Quantity Rules

Public Assembly,Refrigerant System Residential, Commercial,

Group Probability Institutional Large Mercantile Industrial

A1 High 2 1 3Low 4 4 4

A2 High 5 5 3Low 7 7 7

A3 High 9 9 3Low 9 9 7

B1 High 2, 6 1, 6 3Low 4 4 4

B2 High 5, 6 5, 6 3Low 7 7 7

B3 High 9 9 3Low 9 9 7

Applicable Rules By Occupancy Classification




Public Assembly,Refrigerant System Residential, Commercial,

Group Probability Institutional Large Mercantile Industrial

A1 High 2 1 3Low 4 4 4

A2 High 5 5 3Low 7 7 7

A3 High 9 9 3Low 9 9 7

B1 High 2, 6 1, 6 3Low 4 4 4

B2 High 5, 6 5, 6 3Low 7 7 7

B3 High 9 9 3Low 9 9 7

Applicable Rules By Occupancy Classification




Rule 4 …

“When the quantity of refrigerant in any system exceeds Table 1 amounts, all refrigerant-containing parts, except piping and those parts outside the building, shall be installed in a machinery room constructed in accordance with the provisions of 8.13.”



Refrigerant Safety Classifications

Refrigerant Chemical Name OrComposition (% By Weight)

Methane Series

CFC (or R) –11 Trichlorofluoromethane 75°F A1 1.6 4,000CFC (or R) –12 Dichlorodifluoromethane –22°F A1 12.0 40,000HCFC (or R) –22 Chlorodifluoromethane –41°F A1 9.4 42,000

Ethane Series

CFC (or R) –113 1,1,2–Trichlorotrifluoroethane 118°F A1 1.9 4,000HCFC (or R) –123 2,2–Dichloro–1,1,1–Trifluoroethane 81°F B1 0.4 1,000HFC (or R) –134a 1,1,1,2–Tetrafluoroethane –15°F A1 16.0 60,000HFC (or R) –152a 1,1–Difluoroethane –13°F A2 1.2 7,000

Azeotropes

R–500 R–12 (73.8) / R–152a (26.2) –27°F A1 12.0 47,000R–502 R–22 (48.8) / R–115 (51.2) –49°F A1 19.0 65,000

NormalBoilingPoint

SafetyGroup

lbs/1000cu ft

PPMByVol

Refrig Qty Per Occupied Space



Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements


equipment room design …

Ventilation

Volume requirements for …

Natural ventilation

Mechanical ventilation

Normal rate

Alarm rate



Ventilation

Remote machinery room …

OccupiedBuilding

OccupiedBuilding

RefrigerationSystem

Lean-to Or Other Structure With Natural Ventilation

More Than20 Feet



Ventilation

Natural ventilation

For refrigerating systems installed “outdoors, more than 20 ft from [any] building openings …”

F = G0.5

where:F = free opening area (sq ft)G = mass of refrigerant (lbs)



Ventilation

Normal-rate mechanical ventilation

Needed whenever the equipment room’s occupied

Requirements:

0.5 cfm per sq ft OR 20 cfm per person

Must operate, if necessary for operator comfort, at a volume that limits the temperature rise (T) to no more than 18°F



Ventilation

Alarm-rate mechanical ventilation

Required to exhaust accumulated refrigerant

Q = 100 × G0.5

where:Q = airflow (cu ft per minute)G = mass of refrigerant (lbs)



Ventilation

Suggested exhaust fan location …

Exhaust Fan

6 Feet



Ventilation

Dual-purposeventilation system …

ExhaustAirflow

End View

Plan View

VentilationAirflow