Refrigeration System
Equipment Room Design
The Trane Company
La Crosse, Wisconsin
© American Standard Inc. 1997
ANSI/ASHRAE Standards

Standard 34-1992 …
“Number Designation And Safety Classification
Of Refrigerants”

Standard 15-1994 …
“Safety Code For Mechanical Refrigeration”
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
Standard 34-1992

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.”
“Number Designation And
Safety Classification Of Refrigerants”
© American Standard Inc. 1997
ASHRAE Standard 34-1992 …
Refrigerant Safety Classifications
higher
flammability
Group A3
Group B3
lower
flammability
Group A2
Group B2
no flame
propagation
Group A1
Group B1
lower toxicity
higher toxicity
© American Standard Inc. 1997
ASHRAE Standard 34-1992 …
Refrigerant/Blend Data
Refrig Qty Per
Occupied Space
Refrigerant
Chemical Name Or
Composition (% By Weight)
Normal
Boiling
Point
75°F
–22°F
–41°F
Safety
Group
A1
A1
A1
Lbs/
1000
cu ft
1.6
12.0
9.4
PPM
By
Vol
4,000
40,000
42,000
Methane Series
CFC
(or R) –11
CFC
(or R) –12
HCFC (or R) –22
Trichlorofluoromethane
Dichlorodifluoromethane
Chlorodifluoromethane
Ethane Series
CFC
(or R)
HCFC (or R)
HFC
(or R)
HFC
(or R)
1,1,2–Trichlorotrifluoroethane
2,2–Dichloro–1,1,1–Trifluoroethane
1,1,1,2–Tetrafluoroethane
1,1–Difluoroethane
118°F
81°F
–15°F
–13°F
A1
B1
A1
A2
1.9
0.4
16.0
1.2
4,000
1,000
60,000
7,000
R–12 (73.8) / R–152a (26.2)
R–22 (48.8) / R–115 (51.2)
–27°F
–49°F
A1
A1
12.0
19.0
47,000
65,000
Azeotropes
R–500
R–502
–113
–123
–134a
–152a
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
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 For
Mechanical Refrigeration”
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
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”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
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”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
Standard 15-1994
Finally, it applies to …

“… parts or components replaced after
adoption of this code only if they are not
identical in function”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
Standard 15-1994
Provides classification criteria for …

Safety group

Occupancy type

Refrigerating system “probability”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
Standard 15-1994
Provides classification criteria for …

Safety group

Occupancy type

Refrigerating system “probability”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ASHRAE Standard 15-1994 …
Safety Group Classification

Standard 34’s refrigerant safety classifications
higher
flammability
Group A3
Group B3
lower
flammability
Group A2
Group B2
no flame
propagation
Group A1
Group B1
lower toxicity
higher toxicity
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
Standard 15-1994
Provides classification criteria for …

Safety group

Occupancy type

Refrigerating system “probability”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ASHRAE Standard 15-1994 …
Occupancy Classification

Institutional


Public assembly


Where large numbers of occupants can’t vacate quickly
Residential


Occupants can’t readily leave without help
Occupants have complete, independent living facilities
Industrial

Occupancy is restricted only to authorized personnel
© American Standard Inc. 1997
ASHRAE Standard 15-1994 …
Occupancy Classification

Commercial


Large mercantile


Occupants transact business, receive personal
services, or purchase food or other goods
Premises where more than 100 people congregate to
purchase personal merchandise
Mixed

Two or more occupancies share the same building
© American Standard Inc. 1997
ANSI/ASHRAE Standards …
Standard 15-1994
Provides classification criteria for …

Safety group

Occupancy type

Refrigerating system “probability”
“Safety Code For
Mechanical Refrigeration”
© American Standard Inc. 1997
ASHRAE Standard 15-1994 …
Refrigerating System Probability
System
Designation
High Probability
Cooling
Or Heating Source
Air Or Substance
To Be Cooled, Heated
Direct
Indirect
Open Spray
Double Indirect
Open Spray
Low Probability
Indirect
Closed
Indirect
Vented Closed
© American Standard Inc. 1997
ASHRAE Standard 15-1994…
Refrigerant Quantity Rules
Applicable Rules By Occupancy Classification
Refrigerant
Group
System
Probability
Institutional
Public Assembly,
Residential, Commercial,
Large Mercantile
A1
High
Low
2
4
1
4
3
4
A2
High
Low
5
7
5
7
3
7
A3
High
Low
9
9
9
9
3
7
B1
High
Low
2, 6
4
1, 6
4
3
4
B2
High
Low
5, 6
7
5, 6
7
3
7
B3
High
Low
9
9
9
9
3
7
Industrial
© American Standard Inc. 1997
ASHRAE Standard 15-1994 …
Refrigerant Quantity Rules
Applicable Rules By Occupancy Classification
Refrigerant
Group
System
Probability
Institutional
Public Assembly,
Residential, Commercial,
Large Mercantile
A1
High
Low
2
4
1
4
3
4
A2
High
Low
5
7
5
7
3
7
A3
High
Low
9
9
9
9
3
7
B1
High
Low
2, 6
4
1, 6
4
3
4
B2
High
Low
5, 6
7
5, 6
7
3
7
B3
High
Low
9
9
9
9
3
7
Industrial
© American Standard Inc. 1997
ASHRAE Standard 15-1994 …
Refrigerant Quantity Rules
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.”
© American Standard Inc. 1997
ASHRAE Standard 34-1992 …
Refrigerant Safety Classifications
Refrig Qty Per
Occupied Space
Refrigerant
Chemical Name Or
Composition (% By Weight)
Normal
Boiling
Point
75°F
–22°F
–41°F
Safety
Group
A1
A1
A1
lbs/
1000
cu ft
1.6
12.0
9.4
PPM
By
Vol
4,000
40,000
42,000
Methane Series
CFC
(or R) –11
CFC
(or R) –12
HCFC (or R) –22
Trichlorofluoromethane
Dichlorodifluoromethane
Chlorodifluoromethane
Ethane Series
CFC
(or R)
HCFC (or R)
HFC
(or R)
HFC
(or R)
1,1,2–Trichlorotrifluoroethane
2,2–Dichloro–1,1,1–Trifluoroethane
1,1,1,2–Tetrafluoroethane
1,1–Difluoroethane
118°F
81°F
–15°F
–13°F
A1
B1
A1
A2
1.9
0.4
16.0
1.2
4,000
1,000
60,000
7,000
R–12 (73.8) / R–152a (26.2)
R–22 (48.8) / R–115 (51.2)
–27°F
–49°F
A1
A1
12.0
19.0
47,000
65,000
Azeotropes
R–500
R–502
–113
–123
–134a
–152a
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
Ventilation
Volume requirements for …

Natural ventilation

Mechanical ventilation

Normal rate

Alarm rate
© American Standard Inc. 1997
equipment room design …
Ventilation

Remote machinery room …
Occupied
Building
More Than
20 Feet
Occupied
Building
Refrigeration
System
Lean-to Or Other
Structure With
Natural Ventilation
© American Standard Inc. 1997
equipment room design …
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)
© American Standard Inc. 1997
equipment room design …
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
© American Standard Inc. 1997
equipment room design …
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)
© American Standard Inc. 1997
equipment room design …
Ventilation

Suggested exhaust fan location …
Exhaust Fan
6 Feet
© American Standard Inc. 1997
equipment room design …
Ventilation

End View
Exhaust
Airflow
Dual-purpose
ventilation system …
Plan View
Ventilation
Airflow
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
Refrigeration System Placement

Unobstructed space for inspecting and
servicing equipment


Must comply with applicable safety standards and
requirements of the presiding regulatory agency
Clear head room not less than 7.25 ft below
equipment over passageways
© American Standard Inc. 1997
equipment room design …
Refrigeration System Placement

Multiple-chiller equipment room layouts …
Refrigeration
Systems
Air
Inlet
Exhaust
Fan
Exhaust
Fan
Air
Inlet
Exhaust
Fan
Air
Inlet
Refrigeration
Systems
Arrangement A
Refrigeration
Systems
Exhaust
Fan
Arrangement B
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
Doors, Passageways And Access

Equipment room access limited to authorized
personnel

Adequate number and type of doors

No openings to other parts of the building

No “shared” air-handling systems
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
Refrigerant Monitoring
“Detector” must …

Be appropriately sensitive to the refrigerant(s)
in use

Activate alarm and ventilation at TLV®–TWA

“Threshold Limit Value–Time Weighted Average”
© American Standard Inc. 1997
equipment room design …
Refrigerant Monitoring
Sensor location and placement …

Height: 18 inches above the floor

Plan

Continuous ventilation: Between the refrigeration
system and room exhaust

Intermittent ventilation: Close to the refrigeration
system, between it and the room entrance
© American Standard Inc. 1997
equipment room design …
Refrigerant Monitoring

Typical refrigerant monitor installation …
Roof Or Concrete Floor
Occupied Space
Mechanical Equipment Room
Refrigerant
Monitor
Sample-In Tubing
5 Feet
Particle Filter
12–18 Inches
Chiller
© American Standard Inc. 1997
equipment room design …
Refrigerant Monitoring

Suggested sensor placement for intermittent
ventilation …
Refrigeration Systems
Identifies refrigerant sampling points
© American Standard Inc. 1997
equipment room design …
Refrigerant Monitoring

Typical multichannel
scanner application …
Refrigerant Monitor
With Multichannel Option
Pit
Identifies refrigerant sampling points
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
Open-Flame Devices

“No open flames that use combustion air from
the machinery room shall be installed where any
refrigerant is used.”

Exceptions …

Combustion air is ducted from outside and sealed to
prevent refrigerant leakage into the combustion
chamber

A refrigerant detector is used to shut down combustion
automatically if a refrigerant leak occurs
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
Pressure-Relief Piping
Roof

Suggested refrigerant
vent piping …
Support this pipe!
(Alternate Arrangement)
Exterior Wall
Flexible Steel
Connection
Purge Discharge
Vent Line
Rupture Disc
Assembly
15 Feet Above
Ground Level
Drip Leg
(Length As
Needed)
1/4” FL × 1/4” NPT
Drain Valve
© American Standard Inc. 1997
Equipment Room Design

Ventilation

Refrigeration system placement

Doors, passageways and access

Refrigerant monitoring

Open-flame devices

Pressure-relief piping

General requirements
© American Standard Inc. 1997
equipment room design …
General Requirements

Signs

Changing, charging and storing refrigerants

Self-contained breathing apparatus

Two required per equipment room

Emergency shutdown procedure

General maintenance
© American Standard Inc. 1997
®
An American-Standard Company