CMC · California Mechanical Code
What are the refrigerant concentration limits (RCL) and releasable charge limits?
The code limits how much refrigerant can be in a space by using a refrigerant’s RCL and the space volume to compute the maximum releasable charge; flammable refrigerants also have a system cap of 1100 lb without AHJ approval (see § 1104.2 and § 1104.5).
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
The California Mechanical Code requires that the allowable refrigerant in a space be limited so a complete release will not exceed the Refrigerant Concentration Limit (RCL) for that refrigerant; the space volume for that conversion is determined in § 1104.2. For flammable refrigerants there is an absolute total cap of 1100 pounds (unless the Authority Having Jurisdiction approves otherwise) stated in § 1104.5. All design and detection decisions that protect occupied spaces from toxicity, asphyxiation or flammability hazards must follow § 1104.2 and § 1104.5 and the referenced tables and listings in the code .
The single most important rule: use the RCL for the specific refrigerant and the actual volume the refrigerant would disperse into (per § 1104.2) to calculate the maximum releasable charge; for flammable refrigerants also ensure the system totals do not exceed 1100 lb without AHJ approval (§ 1104.5) .
Requirements in detail
Key defined terms (first mentions are bolded)
- Refrigerant Concentration Limit (RCL) — the concentration in air that limits acute toxicity, asphyxiation, and flammability risk; used to convert a concentration limit to an allowable mass for a given space (§ 1104.2) .
- Releasable charge — the maximum mass of refrigerant that could be released into the occupied space in a complete discharge of an independent circuit; it is determined by applying the RCL to the applicable volume (§ 1104.2) .
- Flammable refrigerant total cap — 1100 lb total of Groups A2, B2, A3, B3 (other than A2L/B2L) without AHJ approval (§ 1104.5) .
What you must calculate and check
- Determine the space volume to which a leak would disperse (see § 1104.2.1–1104.2.3 for rules on connected/nonconnected/ventilated spaces). Use that volume when converting the RCL (units shown in ASHRAE/CMC tables) to a releasable mass limit .
- Find the RCL value for the refrigerant (the code references RCL values in the refrigerant tables; e.g., ASHRAE tables in the code list RCL in lb/Mcf) and convert to pounds allowed for your volume .
- For flammable refrigerants (Groups A2, B2, A3, B3 except A2L/B2L) check the total installed charge does not exceed 1100 lb in the installation without AHJ approval (§ 1104.5) .
Decision table — what to check (short, decision-relevant)
| Decision-relevant dimension | Typical value / rule | Code reference |
|---|---|---|
| Space-volume used for conversion | Volume where refrigerant would disperse (see connected/ventilated rules) | § 1104.2.1–1104.2.3 |
| Unit for RCL in tables | RCL listed as lb/Mcf (pounds per 1,000 ft³) — use to compute allowable pounds | RCL table referenced in code (ASHRAE tables) |
| Flammable refrigerant total cap | 1100 lb total of Groups A2, B2, A3, B3 (except A2L/B2L) without AHJ approval | § 1104.5 |
| Institutional occupancies adjustment | RCL value required in §1104.2 shall be reduced by 50% for institutional areas (§1104.3) | § 1104.3 (see §1104.2 context) |
| Ducts/plenums inclusion | Include supply/return duct volumes; suspended-ceiling plenum excluded unless it is part of the air supply/return | § 1104.2.3.2–1104.2.3.3 |
How to convert RCL to a releasable charge (process)
- Identify the refrigerant and its RCL (lb/Mcf) from the code’s refrigerant table (ASHAE-derived tables referenced in the CMC) .
- Determine the applicable space volume (ft³ or Mcf) per § 1104.2.1–1104.2.3 (include ducts where required) .
- Multiply the RCL (lb/Mcf) by the room volume in Mcf (1 Mcf = 1,000 ft³) to get the maximum releasable pounds allowed for that space under § 1104.2 .
- For flammable refrigerants, additionally verify the system total does not exceed 1100 lb without AHJ approval (§ 1104.5) .
Exceptions & special cases
- Machinery rooms, industrial spaces, or isolated equipment may be treated differently: § 1104.4 allows different rules (for example, separated, restricted-access rooms with detectors) — these can permit otherwise restricted refrigerant uses when their conditions are met .
- A2L refrigerants have separate provisions (§ 1104.6) for human comfort systems; occupied spaces must comply with equipment listing and ASHRAE 15 releasable-charge limits and have additional sensor/mitigation requirements .
- Institutional occupancies (hospitals, care facilities) require the RCL value to be reduced by 50% for occupied areas; the total of flammable groups is limited to 550 lb in these areas (§ 1104.3) .
- Listed equipment with small charges (listed self-contained equipment with 0.331 lb of Group A3, for example) may be permitted by listing exceptions — always check the equipment listing and manufacturer instructions as recognized in § 1104.2 and related notes .
Common mistakes
- Not using the correct volume of dispersion: designers often exclude ducts or mistakenly include above-ceiling plenum volumes that are excluded unless part of supply/return — check § 1104.2.3 carefully .
- Applying RCL without checking occupancy adjustments: institutional areas must use a 50% reduced RCL per § 1104.3 .
- Forgetting the flammable refrigerant aggregate cap: even if a room’s releasable charge is within the RCL-based limit, the installed total of Groups A2/B2/A3/B3 must not exceed 1100 lb without AHJ approval (§ 1104.5) .
- Relying solely on manufacturer charge data without verifying the equipment is listed and installed per listing/manufacturer instructions as required in related sections (§ 1104.6.2 and § 1104.2 context) .
Worked example — concrete numbers
Scenario: a small mechanical room directly serves an occupied office. Room volume = 2,000 ft³. Refrigerant selected: R-32.
Step 1 — RCL: From the refrigerant table R‑32 has RCL = 4.8 lb/Mcf (table units are lb per 1,000 ft³) .
Step 2 — Convert volume: 2,000 ft³ = 2.0 Mcf. Use the space volume per § 1104.2.1 rules to confirm this is the controlling volume for dispersion .
Step 3 — Calculate maximum releasable charge for that space: 4.8 lb/Mcf × 2.0 Mcf = 9.6 lb. That means a complete release of more than 9.6 lb of R‑32 into that 2,000 ft³ occupied space would exceed the RCL and therefore require additional mitigation, listing/ventilation, or classification changes under § 1104.2 and related provisions .
Step 4 — Check flammable cap (if R‑32 classified flammable for this purpose): the total installed refrigerant quantity for flammable groups must also be checked against 1100 lb per § 1104.5; even if the room limit is 9.6 lb, the overall system totals must not exceed the § 1104.5 cap without AHJ approval .
Note: R‑32 is an A2L in the code’s classification scheme (lower-flammability); A2L systems for human comfort have their own additional rules in § 1104.6 — always confirm which subsection applies to your application .
Related provisions
- § 1104.2.1–1104.2.3 — Volume calculations and rules for connected/ventilated spaces (use for converting RCL to mass) .
- § 1104.3 — Institutional occupancy reductions and limits (50% reduction; 550 lb cap) .
- § 1104.4 — Industrial occupancies and refrigerated rooms exceptions (separation, restricted access, detectors) .
- § 1104.6 — Special requirements for A2L refrigerants (releasable-charge limits, listing, detection) .
- Table references (refrigerant tables / ASHRAE values) — RCL and OEL numeric values are in the code’s refrigerant tables (see the ASHRAE-derived table referenced in the CMC) .
- § 1106.11 (detectors/alarms) — detector setpoints tied to OEL and RCL and required alarm/ventilation responses .
- § 1112.11 — discharge location rules for pressure‑relief devices that reference RCL for outdoor/indoor termination criteria .
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 1106.2.6. High relevance — show source text
(1) The space(s) containing the machinery is (are) separated from other occupancies by tight construction with tightfitting doors.
(2) Access is restricted to authorized personnel.
(3) Refrigerant detectors are installed with the sensing location and alarm level as required in refrigeration machinery rooms in accordance with Section 1106.2.6.
(4) Open flames and surfaces exceeding 800°F (427°C) shall not be permitted where a Group A2, B2, A3, or B3 refrigerant, is used.
(5) Electrical equipment that is in accordance with Class 1, Division 2, of NFPA 70 where the quantity of a Group A2, B2, A3, or B3 refrigerant in an independent circuit is capable of exceeding 25 percent of the lower flammability limit (LFL) upon release to the space based on the volume determined in accordance with Section 1104.2.1 through Section 1104.2.3.
(6) Refrigerant containing parts in systems exceeding 100 horsepower (74.6 kW) compressor drive power, except evaporators used for refrigeration or dehumidification, condensers used for heating, control and pressure-relief valves for either, low-probability pumps, and connecting piping, are located in a machinery room or outdoors.
[ASHRAE 15:7.2.2]
1104.5 Flammable Refrigerants. The total of Group A2, B2, A3, and B3 refrigerants, other than Group A2L and B2L refrigerants shall not exceed 1100 pounds (498.9 kg) without approval by the Authority Having Jurisdiction. Institutional Occupancies shall comply with Section 1104.3. Machinery rooms required in accordance with Section 1106.0 based on flammability shall be constructed and maintained in accordance with Section 1106.2.1 through Section 1106.2.6 and Section 1106.11 for Group A2L and B2L refrigerants. 1104.6 Group A2L Refrigerants for Human Comfort. High-probability systems using Group A2L refrigerants for human comfort applications shall comply with this section.
[ASHRAE 15:7.6]
1104.6.1 Refrigerant Concentration Limits. Occupied spaces shall comply with the releasable charge limitations of the equipment listing and ASHRAE 15. Unoccupied spaces with refrigerant containing equipment, not including continuous piping or tubing, shall comply with the releasable charge limitations of the equipment listing or Section 1104.6.4. {ASHRAE 15:7.6.1-7.6.1.2}
1104.6.2 Listing and Installation Requirements. Refrigeration systems shall be listed and shall be installed in accordance with listing, the manufacturer’s instructions, and any markings on the equipment restricting the installation. [ASHRAE 15:7.6.2]
1104.6.2.1 Nameplate. The nameplate required by Section 1115.5 shall include a symbol indicating that a flammable refrigerant is used, as specified by the product listing. [ASHRAE 15:7.6.2.1]
1104.6.2.2 Labeling. A label indicating a flammable refrigerant is used shall be placed adjacent to service ports and other locations where service involving components containing refrigerant is performed, as specified by the product listing.
CMC § 4-1 High relevance — show source text
[ASHRAE 34: TABLE 4-1, TABLE 4-2]
REFRIGERANT CHEMICAL FORMULA CHEMICAL NAME1
(COMPOSITION FOR BLENDS)SAFETY
GROUPOEL2
(ppm)RCL (lb/Mcf) LFL8
(lb/Mcf)R-11 CCl3F Trichlorofluoromethane A1 1000 0.39 –– R-12 CCl2F2 Dichlorodifluoromethane A1 1000 5.6 –– R-12B1 CBrClF2 Bromochlorodifluoromethane –– –– –– –– R-13 CClF3 Chlorotrifluoromethane A1 1000 –– –– R-13B1 CBrF3 Bromotrifluoromethane A1 1000 –– –– R-13I1 CF3I Trifluoroiodomethane A1 500 1.0 –– R-14 CF4 Tetrafluoromethane (carbon tetrafluoride) A1 1000 25 –– R-21 CHCl2F Dichlorofluoromethane B1 –– –– –– R-22 CHClF2 Chlorodifluoromethane A1 1000 13 –– R-23 CHF3 Trifluoromethane A1 1000 7.3 –– R-30 CH2Cl2 Dichloromethane (methylene chloride) B1 –– –– –– R-31 CH2ClF Chlorofluoromethane –– –– –– –– R-32 CH2F2 Difluoromethane (methylene fluoride) A2L 1000 4.8 19.1 R-40 CH3Cl Chloromethane (methyl chloride) B2 –– –– –– R-41 CH3F Fluoromethane (methyl fluoride) –– –– –– –– R-50 CH4 Methane A3 1000 –– –– R-113 CCl2FCClF2 1, 1, 2-trichloro-1, 2, 2-trifluoroethane A1 1000 1.2 –– R-114 CClF2CClF2 1, 2-dichloro-1, 1, 2, 2-tetrafluoroethane A1 1000 8.7 –– R-115 CClF2CF3 Chloropentafluoroethane A1 1000 47 –– R-116 CF3CF3 Hexafluoroethane A1 1000 34 –– R-123 CHCl2CF3 2, 2-dichloro-1, 1, 1-trifluoroethane B1 50 3.5 –– R-124 CHClFCF3 2-chloro-1, 1, 1, CMC § 7.6 High relevance — show source text
[ASHRAE 15:7.6]
1104.6.1 Refrigerant Concentration Limits. Occupied spaces shall comply with the releasable charge limitations of the equipment listing and ASHRAE 15. Unoccupied spaces with refrigerant containing equipment, not including continuous piping or tubing, shall comply with the releasable charge limitations of the equipment listing or Section 1104.6.4. {ASHRAE 15:7.6.1-7.6.1.2}
1104.6.2 Listing and Installation Requirements. Refrigeration systems shall be listed and shall be installed in accordance with listing, the manufacturer’s instructions, and any markings on the equipment restricting the installation. [ASHRAE 15:7.6.2]
1104.6.2.1 Nameplate. The nameplate required by Section 1115.5 shall include a symbol indicating that a flammable refrigerant is used, as specified by the product listing. [ASHRAE 15:7.6.2.1]
1104.6.2.2 Labeling. A label indicating a flammable refrigerant is used shall be placed adjacent to service ports and other locations where service involving components containing refrigerant is performed, as specified by the product listing.
[ASHRAE 15:7.6.2.2]
1104.6.2.3 Refrigerant Detection Systems. Refrigerant detection systems shall be in accordance with the listing and ASHRAE 15.
2025 CALIFORNIA MECHANICAL CODE 229
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REFRIGERATION
1104.6.2.4 Refrigerant Concentration Above Limit. When the refrigerant detection system senses a refrigerant exceeding its setpoint, the following actions shall be taken:
(1) The supply air fan of the equipment shall activate with a minimum airflow rate specified by the manufacturer.
(2) Turn off the compressor and all other electrical devices, excluding the control power transformers, control systems, and the supply air fan. The supply air fan shall continue to operate for at least five minutes after the refrigerant detection system has sensed a drop in the refrigerant concentration below the value specified in Section 1104.6.6(b).
Exception: The compressor operation shall not be turned off when the compressor operation reduces the leak rate or the total amount of
released refrigerant to the indoor space.
(3) Any device that controls airflow located within the product or in ductwork that supplies air to the occupied space shall be fully open. Any device that controls airflow shall be listed.
CMC § 7.3.2.1 Medium relevance — show source text
Exceptions: The following closure devices are not considered:
(1) Smoke dampers, fire dampers, and combination smoke/fire dampers that close only in an emergency not associated with a refrigerant leak.
(2) Dampers, such as variable-air-volume (VAV) boxes, that provide limited closure where airflow is not reduced below 10 percent of its maximum (with the fan running). [ASHRAE 15:7.3.2.1] 1104.2.3.2 Plenums. The space above a suspended ceiling shall not be included in calculating the refrigerating system quantity limits unless such space is part of the air supply or return system.
[ASHRAE 15:7.3.2.2] 1104.2.3.3 Supply and Return Ducts. The volume of the supply and return ducts and plenums shall be included when calculating the refrigerating system quantity limits. [ASHRAE 15:7.3.2.3] 1104.3 Institutional Occupancies. The RCL value required in Section 1104.2 shall be reduced by 50 percent for the areas of institutional occupancies. The total of Group A2, B2, A3, and B3 refrigerants shall not exceed 550 pounds (249.5 kg) in the occupied areas and machinery rooms of institutional occupancies. [ASHRAE 15:7.2.1]
Exception: The total of all Group A2L refrigerants shall not be limited in machinery rooms of institutional occupancies.
[OSHPD 1 & 4] Exception: For technology equipment cen- ters not attached to a patient care area the amounts shown in Table 1102.3 may be calculated at 100 percent. 1104.4 Industrial Occupancies and Refrigerated Rooms. Section 1104.2 shall not apply in industrial occupancies and refrigerated rooms where in accordance with the following:
(1) The space(s) containing the machinery is (are) separated from other occupancies by tight construction with tightfitting doors.
(2) Access is restricted to authorized personnel.
(3) Refrigerant detectors are installed with the sensing location and alarm level as required in refrigeration machinery rooms in accordance with Section 1106.2.6.
(4) Open flames and surfaces exceeding 800°F (427°C) shall not be permitted where a Group A2, B2, A3, or B3 refrigerant, is used.
(5) Electrical equipment that is in accordance with Class 1, Division 2, of NFPA 70 where the quantity of a Group A2, B2, A3, or B3 refrigerant in an independent circuit is capable of exceeding 25 percent of the lower flammability limit (LFL) upon release to the space based on the volume determined in accordance with Section 1104.2.1 through Section 1104.2.3.
(6) Refrigerant containing parts in systems exceeding 100 horsepower (74.6 kW) compressor drive power, except evaporators used for refrigeration or dehumidification, condensers used for heating, control and pressure-relief valves for either, low-probability pumps, and connecting piping, are located in a machinery room or outdoors.
[ASHRAE 15:7.2.2]
CMC § 8.2 Medium relevance — show source text
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 lines shall be made in a manner that prevents foreign material or debris from entering the discharge piping.
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REFRIGERATION
(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 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 higherpressure vessel shall be selected to deliver capacity in accordance with Section 1113.5 without exceed ing 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 pressure 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]
CMC § 3.1 Medium relevance — show source text
Reclaimed Refrigerants. Refrigerants reprocessed to the same specifications as new refrigerants by any means, including distillation. Such refrigerants have been chemically analyzed to verify that those specifications have been met.
[ASHRAE 15:3]
Recovered Refrigerants. Refrigerants removed from a system in any condition without necessarily testing or processing them. [ASHRAE 15:3] Recycled Refrigerants. Refrigerants for which contaminants have been reduced by oil separation, removal of noncondensable gases, and single or multiple passes through filter driers or other devices that reduce moisture, acidity, and particulate matter. [ASHRAE 15:3] Refrigerant. A chemical compound intended to be used for heat transfer in a refrigerating system. Refrigerant Concentration Limit (RCL). The refrigerant concentration limit, in air, determined in accordance with this code and intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. [ASHRAE 34:3.1] Refrigerant Designation. The unique identifying alphanumeric value assigned to an individual refrigerant. Refrigerant Safety Classifications. Made up of a letter (A or B), that indicates the toxicity class, followed by a number (1, 2, 2L, or 3), that indicates the flammability class. Refrigerant blends are similarly classified, based on the compositions at their worst cases of fractionation, as separately determined for toxicity and flammability. In some cases, the worst case of fractionation is the original formulation. Flammability Classification. Refrigerants shall be classified for flammability in accordance with one of the following: Class 1. Refrigerants that do not show flame propagation where tested in air at 14.7 pound-force per square inch absolute (psia) (101 kPa) and 140°F (60°C). Class 2. Refrigerants having a lower flammability limit (LFL) of more than 0.00625 pound per cubic foot (lb/ft [3] ) (0.10012 kg/m [3] ) at 140°F (60°C), 14.7 psia (101 kPa), and a heat of combustion of less than 8169 British thermal units per pound (Btu/lb) (1.8988 E+07 J/kg).
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DEFINITIONS
Class 2L. Refrigerants having a lower flammability limit (LFL) of more than 0.00625 pound per cubic foot (lb/ft [3] ) (0.10012 kg/m [3] ) at 140°F (60°C), 14.7 psia (101 kPa), a heat of combustion of less than 8169 British thermal units per pound (Btu/lb) (1.8988 E+07 J/kg), and a maximum burning velocity of 3.9 inches per second (10 cm/s) where tested at 73.4°F (23°C) and 14.7 psia (101 kPa) in dry air. **Class 3.
CMC § 7.3 Medium relevance — show source text
[ASHRAE 15:7.3]
1104.2.2 Nonconnecting Spaces. Where a refrigerating system, or a part thereof, is located in one or more enclosed occupied spaces that do not connect through permanent openings or HVAC ducts, the volume of the smallest occupied space shall be used to determine the refrigerant quantity limit in the system. Where different stories and floor levels connect through an open atrium or mezzanine arrangement, the volume to be used in calculating the refrigerant quantity limit shall be determined by multiplying the floor area of the lowest space by 8.2 feet (2499 mm). [ASHRAE 15:7.3.1]
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REFRIGERATION
1104.2.3 Ventilated Spaces. Where a refrigerating system, or a part thereof, is located within an air handler, in an air distribution duct system, or in an occupied space served by a mechanical ventilation system, the entire air distribution system shall be analyzed to determine the worst-case distribution of leaked refrigerant. The worst case or the smallest volume in which the leaked refrigerant disperses shall be used to determine the refrigerant quantity limit in the system, subject to the criteria in accordance with Section 1104.2.3.1 through Section 1104.2.3.3. [ASHRAE 15:7.3.2]
1104.2.3.1 Closures. Closures in the air distribution system shall be considered. Where one or more spaces of several arranged in parallel are capable of being closed off from the source of the refrigerant leak, their volume(s) shall not be used in the calculation.
Exceptions: The following closure devices are not considered:
(1) Smoke dampers, fire dampers, and combination smoke/fire dampers that close only in an emergency not associated with a refrigerant leak.
(2) Dampers, such as variable-air-volume (VAV) boxes, that provide limited closure where airflow is not reduced below 10 percent of its maximum (with the fan running). [ASHRAE 15:7.3.2.1] 1104.2.3.2 Plenums. The space above a suspended ceiling shall not be included in calculating the refrigerating system quantity limits unless such space is part of the air supply or return system.
[ASHRAE 15:7.3.2.2] 1104.2.3.3 Supply and Return Ducts. The volume of the supply and return ducts and plenums shall be included when calculating the refrigerating system quantity limits. [ASHRAE 15:7.3.2.3] 1104.3 Institutional Occupancies. The RCL value required in Section 1104.2 shall be reduced by 50 percent for the areas of institutional occupancies. The total of Group A2, B2, A3, and B3 refrigerants shall not exceed 550 pounds (249.5 kg) in the occupied areas and machinery rooms of institutional occupancies. [ASHRAE 15:7.2.1]
Exception: The total of all Group A2L refrigerants shall not be limited in machinery rooms of institutional occupancies.
CMC § 403.7 Medium relevance — show source text
1
Table 403.7 Notes 11 & 12BSC BSC-
CGSFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC Adopting Agency
Adopt Entire Chapter
Adopt Entire Chapter as
amended (amended sections
listed below)
Adopt only those sections
that are listed below
Chapter/Section
401.1
401.3
401.3.1
402.1
402.1.2
402.2
402.3
403.0
403.7.2.1 – 403.7.2.4
405.3
406.0
407.0
408.0
409.0
410.0
411.0
412.0
413.0
414.0
415.0
416.0 – 416.2
416.3
416.4
417.0
418.0
419.0
Table 4-A
Table 4-B
Table 4-C
Table 402.1
Table 403.7_Notes 11 & 12_BSC BSC-
CGSFM 1 2 1-AC AC ** SS** ** SS/CC** 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6 Adopting Agency
Adopt Entire Chapter
Adopt Entire Chapter as
amended (amended sections
listed below)
Adopt only those sections
that are listed below
Chapter/Section
401.1
401.3
401.3.1
402.1
402.1.2
402.2
402.3
403.0
403.7.2.1 – 403.7.2.4
405.3
406.0
407.0
408.0
409.0
410.0
411.0
412.0
413.0
414.0
415.0
416.0 – 416.2
416.3
416.4
417.0
418.0
419.0
Table 4-A
Table 4-B
Table 4-C
Table 402.1
Table 403.CMC § 1102.3. Medium relevance — show source text
(3) The refrigerant detector shall have a set point not greater than the applicable Occupational Exposure Limit (OEL) value in accordance with Table 1102.3. The applicable OEL value shall be the lowest OEL value for any refrigerant designation in the machinery room. For refrigerants that do not have an OEL value in Table 1102.3, use a value determined in accordance with the OEL as defined by ASHRAE 34 where approved by the Authority Having Jurisdiction.
(4) The refrigerant detector shall have a set point not more than the applicable Refrigerant Concentration Limit (RCL) value in accordance with Table 1102.3. The applicable RCL value shall be the lowest RCL value for any refrigerant designation in the machinery room. For refrigerants that do not have a RCL value in Table 1102.3, use a value determined in accordance with the RCL as defined by ASHRAE 34 where approved by the Authority Having Jurisdiction.
(5) The refrigerant detector shall provide a means for automatic self-testing and shall be in accordance with Section 1106.11.10.4. The refrigerant detector shall be tested during installation and annually thereafter in accordance with the fire code, or at an interval not exceeding the manufacturer’s installation instructions, whichever is less. Testing shall verify compliance with the alarm set points and response times per Section 1106.11.10 and Section 1106.11.11. [ASHRAE 15:8.13.9]
1106.11.10 Alarms. Alarms required by Section 1106.11.8 shall comply with Section 1106.11.10.1 through Section 1106.11.10.4.
1106.11.10.1 Visual and Audio. The alarm shall
have visual and audible annunciation inside the refrigerating machinery room and outside each entrance to the refrigerating machinery room.
[ASHRAE 15:8.13.10.1] 1106.11.10.2 Detector Activation. The refrigerant detector set points shall activate an alarm in accordance with the type of reset in Table 1106.11.10.2. Manual reset type alarms shall have the reset located inside the refrigerating machinery room. [ASHRAE 15:8.13.10.2]
TABLE 1106.11.10.2 REFRIGERANT DETECTOR SET POINTS, RESPONSE TIMES, ALARMS, AND VENTILATION LEVELS
[ASHRAE 15: TABLE 8-1]
LIMIT VALUE RESPONSE TIME
(seconds)ALARM TYPE ALARM RESET TYPE VENTILATION RATE VENTILATION
RESET TYPESet point≤ OEL ≤300 Trouble Alarm Automatic Level 1 Automatic Set point≤ RCL ≤15 Emergency Alarm Manual Level 2 Manual 2025 CALIFORNIA MECHANICAL CODE 235
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REFRIGERATION
1106.11.10.3 Alarm Levels. Alarms set at levels
CMC § 1103.2 Medium relevance — show source text
1103.2 Classification of Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 227
1103.3 Higher Flammability Refrigerants . . . . . . . . . . . . . . . . . 227
1104.0 Requirements for Refrigerant and Refrigeration System Use . . . 227
1104.1 System Selection . . . . . . . . . . . . . 227
1104.2 Refrigerant Concentration Limit (RCL) . . . . . . . . . . . . . . . . . . 227
Table 1104.1 Permissible Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 228
1104.3 Institutional Occupancies . . . . . . . 229
1104.4 Industrial Occupancies and Refrigerated Rooms . . . . . . . . . . . 229
1104.5 Flammable Refrigerants . . . . . . . . 229
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TABLE OF CONTENTS
1104.6 Group A2L Refrigerants for Human Comfort . . . . . . . . . . . . . . 229
110.4.7 Applications for Human Comfort and for Nonindustrial
Occupancies. . . . . . . . . . . . . . . . . 230
1104.8 Refrigerant Type and Purity . . . . . 230
1104.9 Changing Refrigerants . . . . . . . . . 231
1105.0 General Requirements . . . . . . . . . 231
1105.1 Human Comfort . . . . . . . . . . . . . . 231
1105.2 Supports and Anchorage . . . . . . . 231
1105.3 Access . . . . . . . . . . . . . . . . . . . . . 231
1105.4 Illumination and Service
Receptacles . . . . . . . . . . . . . . . . . 231
1105.5 Ventilation of Rooms
Containing Condensing Units . . . . 231
1105.6 Prohibited Locations . . . . . . . . . . . 232
1105.7 Condensate . . . . . . . . . . . . . . . . . 232
1105.8 Defrost . . . . . . . . . . . . . . . . . . . . . 232
1105.9 Overflows . . . . . . . . . . . . . . . . . . . 232
1105.10 Condensate, Defrost, and Overflow Disposal. . . . . . . . . . . . . 232
1105.11 Refrigerant Port Protection . . . . . . 232
1105.12 Storage . . . . . . . . . . . . . . . . . . . . . 232
1106.0 Refrigeration Machinery Rooms . . 232
1106.1 Where Required . . . . . . . . . . . . . . 232
1106.2 Refrigeration Machinery Room, General Requirements . . . . . . . . . 232
CMC § 1013.7 Medium relevance — show source text
1013.7 Unfired Pressure Vessels . . . . . . . 221
1014.0 Operation and Maintenance of
Boilers and Pressure Vessels. . . . 221
1014.1 General. . . . . . . . . . . . . . . . . . . . . 221
Table 1003.2.1 Controls and Limit Devices for
Automatic Boilers . . . . . . . . . . . . . 222
CHAPTER 11 REFRIGERATION . . . . . . . . . . . . 225
1101.0 General. . . . . . . . . . . . . . . . . . . . . 227
1101.1 Applicability. . . . . . . . . . . . . . . . . . 227
1101.2 Equipment . . . . . . . . . . . . . . . . . . 227
Part I Refrigeration Systems . . . . . . . . 227
1102.0 Refrigeration Systems . . . . . . . . . 227
1102.1 General. . . . . . . . . . . . . . . . . . . . . 227
1102.2 Ammonia Refrigeration Systems . . 227
1102.3 Refrigerants . . . . . . . . . . . . . . . . . 227
1103.0 Classification . . . . . . . . . . . . . . . . 227
1103.1 Classification of Refrigerants . . . . 227
Table 1103.1.1 Refrigerant Safety Group Classifications. . . . . . . . . . . . . . . . 227
1103.2 Classification of Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 227
1103.3 Higher Flammability Refrigerants . . . . . . . . . . . . . . . . . 227
1104.0 Requirements for Refrigerant and Refrigeration System Use . . . 227
1104.1 System Selection . . . . . . . . . . . . . 227
1104.2 Refrigerant Concentration Limit (RCL) . . . . . . . . . . . . . . . . . . 227
Table 1104.1 Permissible Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 228
1104.3 Institutional Occupancies . . . . . . . 229
1104.4 Industrial Occupancies and Refrigerated Rooms . . . . . . . . . . . 229
1104.5 Flammable Refrigerants . . . . . . . . 229
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TABLE OF CONTENTS
1104.6 Group A2L Refrigerants for Human Comfort . . . . . . . . . . . . . . 229
110.4.7 Applications for Human Comfort and for Nonindustrial
Occupancies. . . . . . . . . . . . . . . . . 230
1104.8 Refrigerant Type and Purity . . . . . 230
1104.9 Changing Refrigerants . . . . . . . . . 231
CMC § 9.5.2 Medium relevance — show source text
relief-valve inlet. [ASHRAE 15:9.5.2]
1112.11 Discharge from Pressure-Relief Devices. 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 discharge to the interior of a building where in accordance with all of the following:
(1) The system contains less than 110 pounds (49.9 kg) of a Group A1 or A2L refrigerant.
(2) The system contains less than 6.6 pounds (2.99 kg) of a Group A2, B1, B2 or B2L refrigerant.
(3) The system does not contain any quantity of a Group A3 or B3 refrigerant.
(4) The system is 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 lines shall be made in a manner that prevents foreign material or debris from entering the discharge piping.
242 2025 CALIFORNIA MECHANICAL CODE
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REFRIGERATION
Frequently asked questions
What does RCL stand for and why is it important?
RCL means Refrigerant Concentration Limit and it is the concentration (expressed in the code tables) used to limit acute toxicity, asphyxiation, and flammability risk. The RCL is the basis for converting a space volume to an allowable releasable refrigerant mass under § 1104.2 .
Where do I find numeric RCL values for a refrigerant?
Numeric RCL values are listed in the refrigerant tables referenced in Chapter 11 (ASHRAE-derived tables); the CMC reproduces these table values (units commonly shown as lb/Mcf) — see the refrigerant tables in the code text .
If my room is served by an air handler, do I include duct volume?
Yes — for systems located in or connected to air handlers or duct systems, include the worst-case distribution volume (supply/return ducts and plenums where applicable) per § 1104.2.3 when determining the volume for the RCL conversion .
Do flammable refrigerants have a system-level cap?
Yes. The total of Group A2, B2, A3, and B3 refrigerants (other than A2L/B2L) shall not exceed 1100 pounds without AHJ approval per § 1104.5 .
What if I’m designing for a hospital or institutional space?
Institutional occupancies require the RCL value in § 1104.2 to be reduced by 50% and impose a lower total cap (550 lb) for applicable flammable groups; see § 1104.3 for details .
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