Permissible Locations of Ammonia Refrigeration Equipment
ANSI/IIAR 2-2014 Addendum A Chapter 4 Location of Ammonia Refrigeration Machinery, prescribes the acceptable locations for installing ammonia refrigeration equipment. In general, it is expected that equipment will be installed inside a machinery room, but four alternatives are permitted.
Exception 1 – Listed Equipment
4.2.1 allows listed equipment containing not more than 6.6 lbs of ammonia and installed in accordance with the listing and manufacturer’s instructions to be installed in any occupancy. The language used in this paragraph was taken from ASHRAE 15 and rarely applies to ammonia refrigeration systems.
Exception 2 – Outdoor Installation
4.2.2 allows equipment to be installed outdoors, so long as the equipment is at least 20 ft from any openings to a building, except openings to the machinery room and industrial occupancies. Equipment may be located close to machinery room or industrial occupancy openings since ammonia equipment is allowed in those spaces and therefore, no greater danger is presented by having the equipment installed directly outside the space.
Exception 3 – Industrial Occupancy
4.2.3 allows evaporators, condensers, low-probability pumps, valves, and systems (or portions thereof) with less than 100 HP to be installed outside machinery rooms in industrial occupancies. ANSI/IIAR 1-2017 defines an industrial occupancy as “A premises or a portion thereof that is not open to the public, where access is controlled such that only authorized personnel are admitted and that is used to manufacture, process, or store goods.” Vessels are notably missing from the list of equipment that can be installed in an industrial occupancy, but so long as the vessel is integral to an evaporator, it may be considered part of the evaporator. In other words, it is unacceptable to install a high pressure receiver in a cold room or processing area, but a surge drum that supplies an evaporator is permissible.
Exception 4 – Public Assembly, Commercial, Residential, and Large Mercantile Occupancies
4.2.4 allows ammonia refrigeration systems to be installed in the occupancy classes listed above, provided that a full discharge of the system will not cause the concentration in any room to exceed 300 ppm. This exception is essentially limited to ultra-low charge systems.
IIAR Standards Committee Interpretation IIAR SC 2019-01 provides additional clarification on this matter.