In the recently released Internation Fire Code (IFC) 2021 edition, the newly designated Section 608 – Mechanical Refrigeration, the code references IIAR 2, 6, 7, 8, and 9 when the refrigerant used is anhydrous ammonia (NH3). The 2021 edition still has many of the long-time requirements that will apply to NH3 systems, such as “emergency access” and more. Here are my favorites and the IIAR references:
SECTION 608
MECHANICAL REFRIGERATION
608.1 Scope.
Refrigeration systems shall be installed in accordance with the International Mechanical Code.
608.1.1 Refrigerants other than ammonia.
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.
608.1.2 Ammonia refrigeration.
Refrigeration systems using ammonia refrigerant and the buildings in which such systems are installed shall comply with IIAR 2 for system design; IIAR 6 for inspection, testing, and maintenance; and IIAR 7 for operating procedures.
Decommissioning of ammonia refrigeration systems shall comply with IIAR 8, and engineering practices for existing ammonia refrigeration systems shall be in accordance with IIAR 9.
(emphasis by me)
608.6 Access.
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.
608.7 Testing of equipment.
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 608.7.1. 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.
608.7.1 Periodic testing.
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.
1. Treatment and flaring systems.
2. Valves and appurtenances necessary to the operation of emergency refrigeration control boxes.
3. Fans and associated equipment intended to operate emergency ventilation systems.
4. Detection and alarm systems.
608.8 Emergency signs.
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.
605.8608.9 Refrigerant detection.
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 608.9.1.
608.11 Emergency pressure control system.
Permanently installed refrigeration systems in machinery rooms 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 608.11.1 and 608.11.2.
608.11.1 Automatic crossover valves.
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 608.11.1.1 through 608.11.1.3.
608.11.1.1 Overpressure limit set point.
Automatic crossover valves shall be arranged to automatically relieve excess system pressure to a lower pressure zone if the pressure in a high- or intermediate-pressure zone rises to within 90 percent of the set point for emergency pressure relief devices.
608.11.1.2 Manual operation.
Where required by the fire code official, automatic crossover valves shall be capable of manual operation.
608.11.1.3 System design pressure.
Refrigeration system zones that are connected to a higher pressure zone by an automatic crossover valve shall be designed to safely contain the maximum pressure that can be achieved by interconnection of the two zones.
608.11.2 Automatic emergency stop.
An automatic emergency stop feature shall be provided in accordance with Sections 608.11.2.1 and 608.11.2.2.
608.11.2.1 Operation of an automatic crossover valve.
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.
608.11.2.2 Overpressure in low-pressure zone.
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.
608.12 Storage, use, and handling.
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.
SAFTENGH NOTE:
Chapter 50 – Hazardous Materials – General Provisions
Chapter 53 – Compressed Gases
Chapter 55 – Cryogenic Fluids
Chapter 57 – Flammable and Combustible Liquids
608.13 Discharge and termination of pressure relief and purge systems.
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 608.13.2 through 608.13.4.
…
608.13.2 Flammable refrigerants.
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 608.13.5 or a flaring system in accordance with Section 608.13.6.
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 .
608.13.3 Toxic and highly toxic refrigerants.
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 608.13.5 or a flaring system in accordance with Section 608.13.6.
608.13.4 Ammonia refrigerant.
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:
1. Directly to atmosphere where the fire code official determines, on review of an engineering analysis prepared in accordance with Section 104.8.2, that a
fire, health, or environmental hazard would not result from atmospheric discharge of ammonia.
2. Through an approved treatment system in accordance with Section 608.13.5.
3. Through a flaring system in accordance with Section 608.13.6.
4. Through an approved ammonia diffusion system in accordance with Section 608.13.7.
5. 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.
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