UL continues investigation of dry sprinklers
Underwriters Laboratories Inc. (UL) is still seeking data pertaining to the operation of dry sprinklers over an extended period of time. The information is needed to help UL prepare recommendations for revising National Fire Protection Association (NFPA) 25, Standard for Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.
UL initially issued a public notice in January, reporting that laboratory tests it had conducted on dry sprinklers taken from field installations indicated that the sprinklers may fail to operate under certain fire conditions if the sprinklers are exposed to harsh environmental conditions over an extended period of time. The malfunctioning sprinklers were typically installed in areas where temperatures may fall below freezing.
At the time UL issued its January notice, it had tested fewer than 100 samples taken from 16 installation locations. It found that 62 percent of the samples needed pressures greater than seven psi to discharge water from the sprinkler. Severe corrosion prevented some sprinklers from operating. The sprinklers involved were manufactured from 1967 to 1996.
According to UL, it may be necessary to change that section of NFPA 25 that recommends that dry sprinklers be replaced, or samples be submitted to a recognized laboratory for field service testing, after being in service for 50 years. “Given the extreme environments in which these units may be installed, their functional life could be reduced to a time period of less than 50 years and, in some cases, significantly less that 50 years,” UL explains.
In addition to collecting the sprinkler systems for testing, UL would like information pertaining to field experience with dry sprinklers and the current 50-year interval for field testing, as specified in NFPA 25. Information, data, or samples should be sent to Kerry Bell, associate managing engineer, Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062; (847) 272-8800, ext. 42629; e-mail: bellk@ul.com.
