// CODE SNIPPET
Section 605 Mechanical Refrigeration
JUMP TO FULL CODE CHAPTER
Where a refrigerant other than ammonia is used, refrigeration systems and the buildings in which such systems are installed shall be in accordance with ASHRAE 15.
Refrigeration systems using ammonia refrigerant and the buildings in which such systems are installed shall comply with IIAR-2 for system design and installation and IIAR-7 for operating procedures. Decommissioning of ammonia refrigeration systems shall comply with IIAR-8.
The use and purity of new, recovered and reclaimed refrigerants shall be in accordance with the International Mechanical Code.
Refrigerants shall be classified in accordance with the International Mechanical Code.
A change in the type of refrigerant in a refrigeration system shall be in accordance with the International Mechanical Code.
Access to refrigeration systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant shall be provided for the fire department at all times as required by the fire code official.
Refrigeration equipment and systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant shall be subject to periodic testing in accordance with Section 605.6.1. Records of tests shall be maintained. Tests of emergency devices or systems required by this chapter shall be conducted by persons trained and qualified in refrigeration systems.
The following emergency devices or systems shall be periodically tested in accordance with the manufacturer's instructions and as required by the fire code official.
- Treatment and flaring systems.
- Valves and appurtenances necessary to the operation of emergency refrigeration control boxes.
- Fans and associated equipment intended to operate emergency ventilation systems.
- Detection and alarm systems.
Refrigeration units or systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant shall be provided with approved emergency signs, charts and labels in accordance with NFPA 704. Hazard signs shall be in accordance with the International Mechanical Code for the classification of refrigerants listed therein.
Machinery rooms shall be provided with a refrigerant detector with an audible and visible alarm. Where ammonia is used as the refrigerant, detection shall comply with IIAR 2. For refrigerants other than ammonia, refrigerant detection shall comply with Section 605.8.1
A detector, or a sampling tube that draws air to a detector, shall be provided at an approved location where refrigerant from a leak is expected to accumulate. The system shall be designed to initiate audible and visible alarms inside of and outside each entrance to the refrigerating machinery room and transmit a signal to an approved location where the concentration of refrigerant detected exceeds the lesser of the following:
- The corresponding TLV-TWA values shown in the International Mechanical Code for the refrigerant classification.
- Twenty-five percent of the lower flammable limit (LFL).
Detection of a refrigerant concentration exceeding the upper detection limit or 25 percent of the lower flammable limit (LFL), whichever is lower, shall stop refrigerant equipment in the machinery room in accordance with Section 605.9.1.
Where flammable refrigerants are used and compliance with Section 1106 of the International Mechanical Code is required, remote control of the mechanical equipment and appliances located in the machinery room as required by Sections 605.9.1 and 605.9.2 shall be provided at an approved location immediately outside the machinery room and adjacent to its principal entrance.
A clearly identified switch of the break-glass type or with an approved tamper-resistant cover shall provide off-only control of refrigerant compressors, refrigerant pumps and normally closed automatic refrigerant valves located in the machinery room. Additionally, this equipment shall be automatically shut off when the refrigerant vapor concentration in the machinery room exceeds the vapor detector's upper detection limit or 25 percent of the LEL, whichever is lower.
A clearly identified switch of the break-glass type or with an approved tamper-resistant cover shall provide on-only control of the machinery room ventilation fans.
Permanently installed refrigeration systems containing more than 6.6 pounds (3 kg) of flammable, toxic or highly toxic refrigerant or ammonia shall be provided with an emergency pressure control system in accordance with Sections 605.10.1 and 605.10.2.
Each high- and intermediate-pressure zone in a refrigeration system shall be provided with a single automatic valve providing a crossover connection to a lower pressure zone. Automatic crossover valves shall comply with Sections 605.10.1.1 through 605.10.1.3.
Where required by the fire code official, automatic crossover valves shall be capable of manual operation.
An automatic emergency stop feature shall be provided in accordance with Sections 605.10.2.1 and 605.10.2.2.
Operation of an automatic crossover valve shall cause all compressors on the affected system to immediately stop. Dedicated pressure-sensing devices located immediately adjacent to crossover valves shall be permitted as a means for determining operation of a valve. To ensure that the automatic crossover valve system provides a redundant means of stopping compressors in an overpressure condition, high-pressure cutout sensors associated with compressors shall not be used as a basis for determining operation of a crossover valve.
The lowest pressure zone in a refrigeration system shall be provided with a dedicated means of determining a rise in system pressure to within 90 percent of the set point for emergency pressure relief devices. Activation of the overpressure sensing device shall cause all compressors on the affected system to immediately stop.
Flammable and combustible materials shall not be stored in machinery rooms for refrigeration systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant. Storage, use or handling of extra refrigerant or refrigerant oils shall be as required by Chapters 50, 53, 55 and 57.
Pressure relief devices, fusible plugs and purge systems discharging to the atmosphere from refrigeration systems containing flammable, toxic or highly toxic refrigerants or ammonia shall comply with Sections 605.12.2 through 605.12.4.
Discharge piping and devices connected to the discharge side of a fusible plug or rupture member shall have provisions to prevent plugging the pipe in the event the fusible plug or rupture member functions.
Systems containing more than 6.6 pounds (3 kg) of flammable refrigerants having a density equal to or greater than the density of air shall discharge vapor to the atmosphere only through an approved treatment system in accordance with Section 605.12.5 or a flaring system in accordance with Section 605.12.6. Systems containing more than 6.6 pounds (3 kg) of flammable refrigerants having a density less than the density of air shall be permitted to discharge vapor to the atmosphere provided that the point of discharge is located outside of the structure at not less than 15 feet (4572 mm) above the adjoining grade level and not less than 20 feet (6096 mm) from any window, ventilation opening or exit.
Systems containing more than 6.6 pounds (3 kg) of toxic or highly toxic refrigerants shall discharge vapor to the atmosphere only through an approved treatment system in accordance with Section 605.12.5 or a flaring system in accordance with Section 605.12.6.
Systems containing more than 6.6 pounds (3 kg) of ammonia refrigerant shall discharge vapor to the atmosphere in accordance with one of the following methods:
- Directly to atmosphere where the fire code official determines, on review of an engineering analysis prepared in accordance with Section 104.7.2, that a fire, health or environmental hazard would not result from atmospheric discharge of ammonia.
- Through an approved treatment system in accordance with Section 605.12.5.
- Through a flaring system in accordance with Section 605.12.6.
- Through an approved ammonia diffusion system in accordance with Section 605.12.7.
- By other approved means.
Exception: Ammonia/water absorption systems containing less than 22 pounds (10 kg) of ammonia and for which the ammonia circuit is located entirely outdoors.
Treatment systems shall be designed to reduce the allowable discharge concentration of the refrigerant gas to not more than 50 percent of the IDLH at the point of exhaust. Treatment systems shall be in accordance with Chapter 60.
Flaring systems for incineration of flammable refrigerants shall be designed to incinerate the entire discharge. The products of refrigerant incineration shall not pose health or environmental hazards. Incineration shall be automatic upon initiation of dis-charge, shall be designed to prevent blowback and shall not expose structures or materials to threat of fire. Standby fuel, such as LP-gas, and standby power shall have the capacity to operate for one and one-half the required time for complete incineration of refrigerant in the system. Standby electrical power, where required to complete the incineration process, shall be in accordance with Section 1203.
Ammonia diffusion systems shall include a tank containing 1 gallon of water for each pound of ammonia (8.3 L of water for each 1 kg of ammonia) that will be released in 1 hour from the largest relief device connected to the discharge pipe. The water shall be prevented from freezing. The discharge pipe from the pressure relief device shall distribute ammonia in the bottom of the tank, but not lower than 33 feet (10 058 mm) below the maximum liquid level. The tank shall contain the volume of water and ammonia without overflowing.
Exhaust from mechanical ventilation systems serving refrigeration machinery rooms containing flammable, toxic or highly toxic refrigerants, other than ammonia, capable of exceeding 25 percent of the LFL or 50 percent of the IDLH shall be equipped with approved treatment systems to reduce the discharge concentrations to those values or lower.
The fire code official shall be notified immediately when a discharge becomes reportable under state, federal or local regulations in accordance with Section 5003.3.1.
A record of refrigerant quantities brought into and removed from the premises shall be maintained.
Where refrigerant of Groups A2, A3, B2 and B3, as defined in the International Mechanical Code, are used, refrigeration machinery rooms shall conform to the Class I, Division 2 hazardous location classification requirements of NFPA 70.
Exceptions:
- Ammonia machinery rooms that are provided with ventilation in accordance with Section 1106.3 of the International Mechanical Code.
- Machinery rooms for systems containing Group A2L refrigerants that are provided with ventilation in accordance with Section 605.17.
Machinery rooms with systems containing Group A2L refrigerants shall comply with Sections 605.17.1 through 605.17.3.
Exception: Machinery rooms conforming to the Class 1, Division 2 hazardous location classification requirements of NFPA 70.
The machinery room shall be provided with a refrigerant detection system. The refrigerant detection system shall be in accordance with Section 605.8 and all of the following:
- The detectors shall activate at or below a refrigerant concentration of 25 percent of the LFL.
- Upon activation, the detection system shall activate the emergency ventilation system in Section 605.17.3.
- The detection, signaling and control circuits shall be supervised.
An emergency ventilation system shall be provided at the minimum exhaust rate specified in ASHRAE 15 or Table 605.17.2. Shut down of the emergency ventilation system shall be by manual means.
TABLE [M] 605.17.2
MINIMUM EXHAUST RATE
| REFRIGERANT | Q (m3/sec) | Q (cfm) |
| R32 | 15.4 | 32,600 |
| R143a | 13.6 | 28,700 |
| R444A | 6.46 | 13,700 |
| R444B | 10.6 | 22,400 |
| R445A | 7.83 | 16,600 |
| R446A | 23.9 | 50,700 |
| R447A | 23.8 | 50,400 |
| R451A | 7.04 | 15,000 |
| R451B | 7.05 | 15,000 |
| R1234yf | 7.80 | 16,600 |
| R1234ze(E) | 5.92 | 12,600 |
The point of discharge to the atmosphere shall be located outside of the structure at not less than 15 feet (4572 mm) above the adjoining grade level and not less than 20 feet (6096 mm) from any window, ventilation opening or exit.
Related Code Sections
Section 605 Building Services and Systems, Mechanical Refrigeration
Refrigeration systems shall be installed in accordance with the International Mechanical Code ...
Section 608 Building Services and Systems, Mechanical Refrigeration
Refrigeration systems shall be installed in accordance with the International Mechanical Code ...
608.9 Building Services and Systems, Refrigerant Detection
of refrigerant detected exceeds the lesser of the following: The corresponding TLV-TWA values shown in the International Mechanical Code ...
Fire Code 2021 of Colorado > 6 Building Services and Systems > 608 Mechanical Refrigeration > 608.9 Refrigerant Detection
605.14 Building Services and Systems, Notification of Refrigerant Discharges
The fire code official shall be notified immediately when a discharge becomes reportable under state, federal or local regulations in accordance ...
Fire Code 2018 of Colorado > 6 Building Services and Systems > 605 Mechanical Refrigeration > 605.14 Notification of Refrigerant Discharges
605.4 Building Services and Systems, Change in Refrigerant Type
A change in the type of refrigerant in a refrigeration system shall be in accordance with the International Mechanical Code ...
Fire Code 2018 of Colorado > 6 Building Services and Systems > 605 Mechanical Refrigeration > 605.4 Change in Refrigerant Type