IIAR Code Advocacy Update By Jeffrey M. Shapiro, PE., FSFPE
Fire Sprinklers and Ammonia Refrigeration…A Good Mix?
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ecently, I participated in a lively email exchange among industry icons regarding the appropriateness of installing fire sprinklers in ammonia machinery rooms and in processing and storage areas of refrigerated facilities. I learned that this has been a topic of discussion and debate for decades, with opinions varying widely. I also learned that U.S. code requirements that mandate fire sprinkler system installations in refrigerated facilities, which have changed over the past two decades, are not well known. In this article, I’ll try to capture the major discussion points, competing views, and of course the code perspective to bring you up to speed on the great fire sprinkler debate. First, the code perspective. The Code Perspective. It may surprise you to learn that refrigerated facilities in the U.S. are not uniquely regulated with respect to requirements that mandate fire sprinklers. Unlike other uses of ammonia in a building, an ammonia refrigeration system will never trigger a hazardous occupancy classification, which in turn mandates a fire sprinkler system in all cases. The exception that grants this allowance for ammonia in refrigeration systems, International Building Code (IBC) Section 307.1, Exception 7, gives credit to the many safeguards that must be designed into ammonia refrigeration systems and the building areas where large quantities of ammonia are present, for example increased ventilation in machinery rooms. As is the case for any facility that processes or stores combustible goods, IBC fire sprinkler mandates for refrigerated facilities are based on certain characteristics of the building, primarily the amount of undivided floor area and the height of the building or occupancy. Factories and warehouses that handle ordinarily combustible material, including food processing and cold storage facilities, are classified by the IBC as Group F-1 and Group S-1 occupancies, respectively. Fire sprinklers are required for both occupancy classes when any of the following conditions exist: • The fire area of the occupancy exceeds 12,000 square feet. • The fire area is located more than three stories above grade plane. • The combined area of all Group F-1 or Group S-1 occupancy fire areas on all floors, including any mezzanines, exceeds 24,000 square feet. • The storage height exceeds 12 feet, which is considered high-piled storage, over a 2,500 square foot or larger
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storage area (there is an option to increase this area allowance to 12,000 square feet, but there are many expensive strings attached). The term “fire area” used in these requirements has special meaning in the IBC. A building may theoretically be subdivided into multiple “fire areas” by using “fire barriers” (another term with special meaning) to remain below the foregoing fire sprinkler installation triggers. However, the concept of subdividing a large processing or storage facility into small compartments using fire-rated walls, fire-rated selfclosing doors, etc. will often be impractical. Plus, while fire sprinklers might be avoided, numerous penalties are assessed by the code for unsprinklered buildings, including reduced exit travel distances and possibly increased requirements for fire resistance of the building structure. It should also be noted that the IBC has other sprinkler system triggers that are based on overall building height and area, but the occupancy-based triggers described above for Group F-1 and Group S-1 occupancies will probably be the first to kick in. Once fire sprinklers are required to protect a building or a fire area, sprinklers must be installed in all refrigerated spaces, machinery rooms, electrical control rooms, etc. There are no exceptions allowing omission of sprinklers from these spaces. In fact, with respect to the question of putting fire sprinklers in electrical rooms, the code has made it quite clear that such protection cannot be omitted simply because the room contains electrical equipment. Section 903.3.1.1.1 states “…Sprinklers shall not be omitted from any room merely because it is damp, of fire-resistance-rated construction or contains electrical equipment.” Do We Really Want Sprinklers in an Ammonia Machinery Room? Several reported concerns have caused industry experts to disagree about the appropriateness of having fire sprinklers in an ammonia machinery room. Positions on this issue are largely split along international lines. The IBC encourages, and often mandates, that fire sprinklers be installed in all machinery rooms. Consider that IBC Table 509 entirely eliminates the required fire-resistance rating for a machinery room enclosure when fire sprinklers are installed. Without sprinklers, a one-hour rated enclosure is required (in older codes, this was three-hours). On the other hand, ISO Draft International Standard (DIS) 5149-3, Section 5-16.2.3 specifically states that fire sprinkler systems are not permitted in ammonia machinery rooms housing systems that have a charge of more than 440 pounds. The Code Update continued on page 10
Condenser | November 2011 | A Publication of the International Institute of Ammonia Refrigeration
