UL Lists fire hydrants under UL 246, the Standard for Hydrants for Fire Protection Service. IN addition, the U.S. Department of Defense has adopted UL 246 as part of its Civil Defense protocol. UL 246 contains basic requiremnets for the performance of fire hydrants supplying water for fire-protection service. Fire hydrants Listed under UL 246 undergo a veariety of tests to verify whether they are strong enough to withstand conditions expected during normal use. They are also tested for pressure loss, strength, leakage and corrosion resistance.
Operational tests help determine that hydrants operate as intended during fire emergencies.
Strength tests ensure that the body of the hydrant is capable of withstanding five times the rated working pressure without rupturing. UL also performs tensile tests on representative test samples of metal and other castings used to form the hydrant. Finally, parts of the hydrant constructed of nonmetallic materials, such as rubber seal rings, are also subjected to physical chemical tests specified in UL 157, Standard for Safety for Gaskets and Seals. Some cities and communities, however, use adapters to modify equipment, since converting threads on older hydrants can be impractical and cost prohibitive. Manufacturers are also required to provide necessary production control, inspection and tests.