The revisions to 2015 IFC, Section 606.12 clarify the code requirements and add references to two (2) International Institute of Ammonia Refrigeration (IIAR) standards and one American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) standard for design and operation of ammonia refrigeration systems. This edition of the IFC also pulls in a lot of Ammonia Refrigeration systems that had been outside the PSM/RMP bubble because they were under 10,000 pounds, but now, the 2015 IFC basically requires new processes to comply with IIAR-2 for system design and installation and IIAR-7 for operating procedures, as well as ASHRAE 15 for other aspects. So essentially, regardless if your process is over 10,000 pounds, all Mechanical Refrigeration systems built in states that adopt this 2015 IFC will be built and managed very much like a PSM/RMP process. Here’s what changes in the 2015 IFC for Mechanical Refrigeration…
606.12 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 606.12.3 through 606.12.5.
606.12.1 Standards
Refrigeration systems and the buildings in which such systems are installed shall be in accordance with ASHRAE 15.
606.12.1.1 Ammonia Refrigeration
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.
SAFTENG NOTES: this means the engine room will be built to IIAR-2 and ASHRAE 15 criteria which includes ventilation and detection requirements as well as actual construction requirements for the structure. IIAR-7 came out in 2013 and defines the minimum requirements for developing operating procedures for closed-circuit ammonia mechanical refrigerating systems. The operating procedures are required to be easy to understand, safe, effective, reliable, and to meet applicable regulatory requirements. Although different than 1910.119(f), this is a HUGE step for the Ammonia Refrigeration industry to REQUIRE written operating procedures for processes under the 10,000 pound PSM/RMP threshold!
606.12.2 Fusible plugs and rupture members
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.
606.12.3 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 606.12.6 or a flaring system in accordance with Section 606.12.7. Systems containing more than 6.6 pound (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 (4,572 mm) above the adjoining grade level and not less than 20 feet (6,096 mm) from any window, ventilation opening or exit.
606.12.4 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 606.12.4 606.12.6 or a flaring system in accordance with Section 606.12.5 606.12.7.
606.12.5 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:
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- Directly to atmosphere when 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 606.12.6.
- Through a flaring system in accordance with Section 606.12.7.
- Through an approved ammonia diffusion system in accordance with Section 606.12.8.
- By other approved means.
Exceptions:
- Ammonia/water absorption systems containing LESS THAN 22 pounds (10 kg) of ammonia AND for which the ammonia circuit is located ENTIRELY outdoors. (Emphasis added by me)
606.12.6 Treatment systems
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 [HIGHLY TOXIC AND TOXIC MATERIALS]
606.12.7 Flaring systems
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 discharge, 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 604.
606.12.7 Ammonia diffusion systems
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 no lower than 33 feet (10,058 mm) below the maximum liquid level. The tank shall contain the volume of water and ammonia without overflowing.