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UL investigates field samples of dry sprinklers

Results may support revisions to NFPA 25

NOTE: This information is from a previously printed press release, newsletter, or other dated document. It is presented here for archival purposes only.

NORTHBROOK, Ill., January 22, 1999 Recent laboratory testing by Underwriters Laboratories Inc. (UL) on dry sprinklers taken from field installations indicates that exposure of these sprinklers to harsh environmental conditions over an extended period of time may cause the sprinkler not to operate under certain fire conditions. These sprinklers are typically installed in areas where temperatures may fall below freezing. To conduct further research and expand the current database, UL is requesting field samples of dry sprinklers for operational testing.

To date, UL has conducted operational tests on less than 100 samples taken from 16 different installation locations. Preliminary test results indicate that 62 percent of the samples required pressures greater than seven psi (pounds per square inch) to discharge water from the sprinkler. Severe corrosion caused some sprinklers not to operate. The years of manufacture for the field samples tested have ranged from 1967 to 1996. More test samples are needed on a wider variety of sprinkler models, years of manufacture and years in service, before final conclusions can be drawn.

The results of UL's investigation to date support the need for revisions to the NFPA (National Fire Protection Association) 25 Standard for Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, which currently requires that dry sprinklers be replaced or that samples be submitted to a recognized laboratory -- such as UL -- for field service testing after those sprinklers have been in service for 50 years.

UL's experience with this type of sprinkler indicates that, given the extreme environments in which these units may be installed, their functional life could be reduced to a time period less than 50 years and, in some cases, significantly less than 50 years.

Accounting for less than three percent of all installed fire sprinklers, dry sprinklers are generally found in locations with harsh environmental conditions, characterized by wide variations in temperature, humidity and corrosive conditions, such as attics, car ports, cold storage structures, parking garages, warehouses, and unheated portions of buildings.

UL will conduct operational testing on dry sprinklers sampled from field installations at no charge to the submitter. It is important to identify these systems and consult with the sprinkler manufacturer or their customer service representatives for information and costs regarding removal and replacement of samples. UL will not reimburse submitters for removal, replacement or shipping costs.
Samples sent to UL for testing should be properly identified with the information described on the Sample Identification Tags, available through UL's Field Sprinkler Sample Testing Program.

In addition to collecting samples for testing, UL is also interested in obtaining any information regarding: (1) specific field experience with dry sprinklers, and (2) the current 50-year interval for field testing, as specified in NFPA 25. Input from the fire sprinkler industry, insurers, property owners, and authorities having jurisdiction will assist in substantiating a proposal to the NFPA 25 Committee to reduce the time interval for dry sprinklers to be tested or replaced.

Information, data or samples for operational testing should be sent to Kerry Bell, Associate Managing Engineer, Underwriters Laboratories Inc. (UL), 333 Pfingsten Road, Northbrook, IL, 60062. Technical questions regarding dry sprinklers can be directed to Mr. Bell at +1-847-272-8800, ext. 42629 or .

Underwriters Laboratories Inc. (UL) is the largest safety testing and conformity assessment organization in North America. More than 14 billion UL Marks appear on products each year, and more than 17,000 types of products are tested at UL's five U.S. testing laboratories, located in Northbrook, Ill.; Melville, N.Y.; Santa Clara, Calif.; Research Triangle Park, N.C.; and Camas, Wash.