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Chapter 11 — REFRIGERATION

1112.11 Discharge from Pressure-Relief Devices.

California Mechanical Code (Title 24, Part 4) · 2022 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

Pressure-relief systems designed for vapor shall comply with Section 1112.11.1 through Section 1112.11.4.1.

1112.11.1 Discharging Location Interior to Build- ing. Pressure-relief devices, including fusible plugs, serving refrigeration systems shall be permitted to dis

REFRIGERATION

charge to the interior of a building where in accordance with the following: (1) The system contains less than 110 pounds (49.9 kg)

of a Group A1 refrigerant. (2) The system contains less than 6.6 pounds (2.99 kg)

of a Group A2, B1 or B2 refrigerant. (3) The system does not contain any quantity of a Group

A3 or B3 refrigerant. (4) The system is not required to be installed in a

machinery room in accordance with Section 1106.0. (5) The refrigerant concentration limits in Section

1104.2 are not exceeded. Refrigeration systems that do not comply with the above requirements shall comply with the requirements of Section 1112.11.2 through Section 1112.11.4. [ASHRAE 15:9.7.8.1] 1112.11.2 Discharging Location Exterior to Build- ing. Pressure-relief devices designed to discharge external to the refrigeration system shall be arranged to discharge outside of a building and shall be in accordance with the following: (1) The point of vent discharge shall be located not less

than 15 feet (4572 mm) above the adjoining ground level. Exception: Outdoor systems containing Group A1 refrigerant shall be permitted to discharge at any elevation where the point of discharge is located in an access-controlled area accessible to authorized personnel only. (2) The point of vent discharge shall be located not less

than 20 feet (6096 mm) from windows, building ventilation openings, pedestrian walkways, or building exits. (3) For heavier-than-air refrigerants, the point of vent

discharge shall be located not less than 20 feet (6096 mm) horizontally from below-grade walkways, entrances, pits or ramps where a release of the entire system charge into such a space would yield a concentration of refrigerant in excess of the RCL. The direct discharge of a relief vent into enclosed outdoor spaces, such as a courtyard with walls on all sides, shall not be permitted where a release of the entire system charge into such a space would yield a concentration of refrigerant in excess of the RCL. The volume for the refrigerant concentration calculation shall be determined using the gross area of the space and a height of 8.2 feet (2499 mm), regardless of the actual height of the enclosed space. (4) The termination point of a vent discharge line shall

be made in a manner that prevents discharged refrigerant from spraying directly onto personnel that are capable of being in the vicinity. (5) The termination point of vent discharge line shall be

made in a manner that prevents foreign material or debris from entering the discharge piping. (6) Relief vent lines that terminate vertically upward

and are subject to moisture entry shall be provided with a drip pocket having a length of not less than 24

2022 CALIFORNIA MECHANICAL CODE 225

REFRIGERATION

inches (610 mm) and having the size of the vent discharge pipe. The drip pocket shall be installed to extend below the first change in vent pipe direction and shall be fitted with a valve or drain plug to permit removal of accumulated moisture. [ASHRAE 15:9.7.8.2] 1112.11.3 Internal Relief. Pressure-relief valves designed to discharge from a higher-pressure vessel into a lower pressure vessel internal to the system shall comply with the following: (1) The pressure-relief valve that protects the higher pressure vessel shall be selected to deliver capacity in accordance with Section 1113.5 without exceeding the maximum allowable working pressure of the higher-pressure vessel accounting for the change in mass flow capacity due to the elevated backpressure. (2) The capacity of the pressure-relief valve protecting

the part of the system receiving a discharge from a pressure-relief valve protecting a higher-pressure vessel shall be not less than the sum of the capacity required in Section 1113.5 plus the mass flow capacity of the pressure-relief valve discharging into that part of the system. (3) The design pressure of the body of the relief valve

used on the higher-pressure vessel shall be rated for operation at the design pressure of the higher-pressure vessel in both pressure-containing areas of the valve. [ASHRAE 15:9.7.8.3] 1112.11.4 Discharge Location, Special Require- ments. Additional requirements for relief device discharge location and allowances shall apply for specific refrigerants in accordance with Section 1112.11.4.1.

[ASHRAE 15:9.7.8.4]

1112.11.4.1 Water (R-718). Where water is the refrigerant, discharge to a floor drain shall be permitted where the following conditions are met: (1) The pressure-relief device set pressure shall not

exceed 15 psig (103 kPa). (2) The floor drain shall be sized to handle the flow

rate from a single broken tube in a refrigerantcontaining heat exchanger. (3) The Authority Having Jurisdiction finds it

acceptable that the working fluid, corrosion inhibitor, and other additives used in this type of refrigeration system are permitted to infrequently be discharged to the sewer system, or a catch tank that is sized to handle the expected discharge shall be installed and equipped with a normally closed drain valve and an overflow line to drain. [ASHRAE 15:9.7.8.4.1]

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▸Contents — California Mechanical Code (Title 24, Part 4)
California Mechanical Code (Title 24, Part 4)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — VENTILATION AIR
  5. Chapter 5 — EXHAUST SYSTEMS
  6. Chapter 6 — DUCT SYSTEMS
  7. Chapter 7 — COMBUSTION AIR
  8. Chapter 8 — CHIMNEYS AND VENTS
  9. Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
  10. Chapter 10 — BOILERS AND PRESSURE VESSELS
  11. ▸Chapter 11 — REFRIGERATION
    Overview
    1. 1101.1 Applicability. Part I governs the design, installation,
    2. 1101.2 Equipment. Equipment for refrigerant recovery,
    3. 1102.1 General. Refrigeration systems using a refrigerant
    4. 1102.2 Ammonia Refrigeration Systems. Refrigeration
    5. 1102.3 Refrigerants. The refrigerant used shall be of a type
    6. 1103.1 Classification of Refrigerants. Refrigerants shall
    7. 1103.2 Classification of Refrigeration Systems.
    8. 1103.3 Higher Flammability Refrigerants. Group A3
    9. 1104.1 System Selection. Refrigeration systems shall be
    10. 1104.2 Refrigerant Concentration Limit. The concentration of r…
    11. 1104.3 Institutional Occupancies. The RCL value
    12. 1104.4 Industrial Occupancies and Refrigerated
    13. 1104.5 Flammable Refrigerants. The total of Group A2,
    14. 1104.6 Applications for Human Comfort and for Non-
    15. 1104.7 Refrigerant Type and Purity. Refrigerants shall
    16. 1104.8 Changing Refrigerants. A change in the type of
    17. 1105.1 Human Comfort. Cooling systems used for human
    18. 1105.2 Supports and Anchorage. Supports and anchorage for refr…
    19. 1105.3 Access. An unobstructed readily accessible opening and …
    20. 1105.4 Illumination and Service Receptacles. In addition to th…
    21. 1105.5 Ventilation of Rooms Containing Condensing
    22. 1105.6 Prohibited Locations. Refrigeration systems or
    23. 1105.7 Condensate. Condensate from air-cooling coils
    24. 1105.8 Defrost. Where defrost cycles are required for portions…
    25. 1105.9 Overflows. Where condensate or defrost liquids are
    26. 1105.10 Condensate, Defrost, and Overflow Dis-
    27. 1105.11 Refrigerant Port Protection. Air conditioning
    28. 1105.12 Storage. Refrigerants and refrigerant oils not
    29. 1106.1 Where Required. Refrigeration systems shall be
    30. 1106.2 Refrigeration Machinery Room, General
    31. 1106.4 Natural Ventilation. Where a refrigerating system
    32. 1106.5 Combustion Air. No open flames that use combustion air …
    33. 1106.6 Airflow. There shall be no airflow to or from an occupi…
    34. 1106.7 Ventilation Intake. Makeup air intakes to replace
    35. 1106.3 Normal Operation. A part of the refrigeration
    36. 1106.8 Maximum Temperature. Ventilation or mechanical cooling …
    37. 1106.9 Refrigerant Parts in Air Duct. Joints and refrigerant-c…
    38. 1106.10 Dimensions. Refrigeration machinery rooms shall
    39. 1106.11 Restricted Access. Access to the refrigeration
    40. 1106.12 Exits. Exits shall comply with the building code for
    41. 1107.1 General. In cases specified in the rules of Section
    42. 1108.1 General. Equipment, piping, ducts, vents, or similar
    43. 1108.2 Electrical. Electrical equipment and installations
    44. 1108.3 Emergency Shut-off. A clearly identified emergency shut…
    45. 1108.4 Installation, Maintenance, and Testing. Detection and a…
    46. 1108.5 Emergency Pressure Control System. Where
    47. 1109.1 Materials. Materials used in the construction and
    48. 1109.2 Joints. Iron or steel pipe joints shall be of approved
    49. 1109.3 Penetration of Piping. Refrigerant piping shall not
    50. 1109.4 Location of Refrigeration Piping. Refrigerant
    51. 1109.5 Underground Piping. Refrigerant piping placed
    52. 1109.6 Support. In addition to the requirements of Section
    53. 1109.7 Pipe Enclosure. Refrigerant piping and tubing
    54. 1109.8 Visual Inspection. Refrigerant piping and joints
    55. 1109.9 Condensation. Piping and fittings that convey
    56. 1109.10 Identification. Piping shall be in accordance with
    57. 1110.1 More than 6.6 Pounds of Refrigerant. Systems
    58. 1110.2 More than 110 Pounds of Refrigerant. Systems
    59. 1110.3 Support. Stop valves installed in copper refrigerant
    60. 1110.4 Access. Stop valves required by Section 1110.0 shall
    61. 1110.5 Identification. Stop valves shall be identified by tagg…
    62. 1111.1 Where Required. Pressure-limiting devices complying wit…
    63. 1111.2 Setting. Pressure limiting devices shall be set in
    64. 1111.3 Location. Stop valves shall not be installed between
    65. 1111.4 Emergency Stop. Activation of a pressure-limiting
    66. 1112.1 General. Refrigeration systems shall be protected by
    67. 1112.2 Positive Displacement Compressor. A positive
    68. 1112.3 Liquid-Containing Portions of Systems. Liquid-containin…
    69. 1112.4 Evaporators. Heat exchanger coils located downstream, o…
    70. 1112.5 Hydrostatic Expansion. Pressure rise resulting
    71. 1112.6 Actuation. Pressure-relief devices shall be directpress…
    72. 1112.7 Stop Valves Prohibited. Stop valves shall not be
    73. 1112.8 Location. Pressure-relief devices shall be connected
    74. 1112.9 Materials. The seats and discs of pressure-relief
    75. 1112.10 Pressure-Relief Device Settings. Pressurerelief valves…
    76. 1112.11 Discharge from Pressure-Relief Devices.
    77. 1112.12 Discharge Piping. The piping used for pressurerelief d…
    78. 1112.13 Rating of Pressure-Relief Device. The rated
    79. 1112.14 Rating of Rupture Members and Fusible
    80. 1113.1 General. Pressure vessels shall be provided with
    81. 1113.2 Type of Protection. Pressure vessels with an internal g…
    82. 1113.3 Discharging into Lowside of System. For pressure-relief…
    83. 1113.4 Parallel Pressure-Relief Devices. Two or more
    84. 1113.5 Discharge Capacity. The minimum required discharge capa…
    85. 1113.6 Three-Way Valve. Pressure vessels of 10 cubic feet
    86. 1114.1 General. Systems containing other than Group A1 or
    87. 1114.2 Design Requirements. Flaring devices shall be
    88. 1114.3 Testing. Flaring systems shall be tested to demonstrate…
    89. 1115.1 General. In addition to labels required elsewhere in
    90. 1115.2 Volume and Type. A condenser, receiver, absorber,
    91. 1115.3 Permanent Sign. In a refrigeration machinery room
    92. 1115.4 Marking of Pressure-Relief Devices. Pressurerelief valv…
    93. 1116.1 Factory Tests. Refrigerant-containing parts of unit
    94. 1116.2 Field Tests. Refrigerant-containing parts of a system t…
    95. 1116.3 Test Gases. Tests shall be performed with dry nitrogen …
    96. 1116.4 Declaration. A dated declaration of test shall be provi…
    97. 1116.5 Brine Systems. Brine-containing portions of a system sh…
    98. 1117.1 Inside Dimensions 6 Inches or Less. Pressure
    99. 1117.2 Inside Dimensions More than 6 Inches. Pressure vessels …
    100. 1117.3 Pressure Vessels for 15 psig or Less. Pressure
    101. 1118.1 General. Refrigeration systems shall be operated and
    102. 1119.1 Applicability. Cooling towers, evaporative condensers, …
    103. 1120.1 General. Cooling towers, evaporative condensers,
    104. 1121.1 General. Drains, overflows, and blow-down provisions sh…
    105. 1122.1 General. Chemical treatment systems shall comply
    106. 1122.2 Automated Control of Cycles of Concentra-
    107. 1123.1 General. Cooling towers, evaporative condensers,
    108. 1124.1 General. Electrical systems shall be in accordance
    109. 1125.1 General. Equipment containing refrigerants as a part
    110. 1126.1 General. Cooling towers, evaporative condensers,
  12. Chapter 12 — HYDRONICS
  13. Chapter 13 — FUEL GAS PIPING
  14. Chapter 14 — PROCESS PIPING
  15. Chapter 15 — SOLAR ENERGY SYSTEMS
  16. Chapter 16 — STATIONARY POWER PLANTS
  17. Chapter 17 — REFERENCED STANDARDS
  18. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  19. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  20. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  21. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  22. Appendix E — SUSTAINABLE PRACTICES
  23. Appendix F — GEOTHERMAL ENERGY SYSTEMS
  24. Appendix G — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  25. Appendix H — EXAMPLE CALCULATION OF OUTDOOR AIR RATE

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