Emergency water sprinkler system for industrial use.

Portland’s Required Field Sample Testing of Automatic Sprinklers

Mar 20th, 2017 - 4:34am

The National Fire Protection Association (NFPA) standard for the inspection, testing and maintenance of water-based fire protection systems (NFPA 25), talks about Portland’s required field sample testing of automatic sprinklers. Portland’s building owners are required to have their installed sprinklers periodically tested by a recognized testing laboratory.

All Portland business owners are responsible for adhering to the NFPA 25 standard in their building codes, which are enforced by location inspection authorities. In addition, most insurance companies require the buildings they insure to have sprinkler systems that comply with this nationally recognized standard.

Per NFPA 25, after 10 years in service, a sample of dry sprinkler heads are required to be tested by a recognized laboratory acceptable to the HJ for field service testing. Where sprinklers have been in service for 50 years, they shall be replaced.  Or, representative samples from one or more sample areas shall be submitted to a recognized testing laboratory acceptable to the authority have jurisdiction for field service test.

AFP Systems, Inc. sends sprinklers sampled from field installations to a certified company. We do this as a service to inspection authorizers, the sprinkler industry, the insurance industry and property owners. Their results assists in assessing the effectiveness of the sprinkler system or the need for replacement of sprinklers currently in service.

As sprinklers age, they must be replaced more often.  For example, standard response sprinklers are required to be tested after 50 years of service. They must then be retested every 10 years. After 75 years the testing frequency increases to every 5 years. As sprinklers age, they may fail more frequently.

As stated in ANPA, where one sprinkler fails the test, all sprinklers represented by that sample must be replaced. Sprinkler designs have improved a lot in recent years. It may be desirable to replace the aging sprinklers rather than continue testing. In addition, if the sample area is small, it may be most cost efficient to replace the sprinklers. A cost benefit analysis will determine if replacement is the best strategy.

The sprinklers being tested undergo a procedure known as a plunge test. The sprinkler is inserted (or plunged) into a device known as a plunge test apparatus. There it is exposed to an airflow with controlled velocity and temperature. The device temperature is higher than the sprinkler’s operating temperature. The sprinkler is pressurized with 5 psi of air pressure. The tester measures the amount of time taken for the fusible element or glass bulb to activate. If the sprinkler fails to operate in the specified amount of time, the sprinkler fails the test. All sprinklers represented by the test sprinkler must be replaced.

Replacing all the sprinklers in a sample area rather than testing is always an option. Dry sprinkler heads have  a much higher failure rate than standard sprinklers. They are also more susceptible to corrosion both internally (when moisture condenses inside the device) and externally. We see corrosion at the water seal and at the weak hole at the bottom of the sprinkler in sprinklers older than 10 years. These sprinklers are usually installed in harsher environments, further compounding this problem. The failure rate of dry-type sprinklers in service for 10 years is approximately 50%. Because of this high failure rate, it is very important that these sprinklers be identified.

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