by Grant Lobdell, General Manager

Whether it be due to corrosion or loading, sprinkler performance often degrades over time.  For this reason, the current 2020 edition of NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems states that sprinklers shall be initially tested or replaced after 50 years in service.  However, a few notable exceptions exist in the standard.  Dry sprinklers, which have had a high failure rate for many years due to the prevalence of the O-ring design, and fast response sprinklers, which are a newer technology compared to standard response sprinklers, shall be initially tested or replaced just 15 years (previously 10 years in prior editions of NFPA 25) or 20 years after install, respectively.  Furthermore, any sprinklers exposed to a harsh environment require testing or replacement every 5 years unless it is specifically listed as corrosion resistant in which case the testing or replacement frequency is decreased to every 10 years.

Test or Replace

To determine if testing or replacement is more cost effective, the building owner and/or their designated representative need to consider the number of sprinklers in the sample area, the condition of those sprinklers, and how often those sprinklers will need to be tested or replaced in the future.  Note that if the building owner chooses to test instead of replace, they will be required to test again every 10 years unless the sprinkler is located in a harsh environment or is 75 years of age or older in which case subsequent testing is to occur every 5 years.  That may seem like the more expensive option given the cost of testing and the fact that each sprinkler removed for the field service test, which is destructive, will still need to be replaced with a new sprinkler, but remember that testing only requires a minimum of 4 or 1% of the sprinklers in the area (whichever is greater) be taken down and sent in for testing.  Because such a small number of sprinklers in an area need to be tested, it will often still be much more economical than the replacement of all sprinklers especially for large sample areas.

Additional Considerations

Sprinklers that feature the O-ring water seal design have a notoriously high failure rate (>50%) at Dyne.  Despite this high failure rate and the fact that UL has not listed a sprinkler featuring an O-ring water seal design in almost 20 years, some do remain in service in the field unfortunately.   Replacement is advised for all sprinklers that feature this design.  However, other designs have had a good track record thus far.  Sprinklers not featuring the O-ring design have failed <5% of the time here at Dyne.

Furthermore, sprinklers manufactured prior to 1920 should not be tested.  They must be replaced regardless of performance in the field service test according to NFPA 25.

Also note that each type of sprinkler should be represented in the sample set sent in for testing.  This means if there are more types of sprinklers in your area than the minimum amount you are required to send in, additional sprinklers beyond the minimum may need to be included in the sample set sent to the laboratory.  However, note that sprinklers that only differ in orientation, which does not impact the field service test, can be considered the same type.

Lastly, regarding the condition of the sprinklers in the sample area, remember that the annual, floor level inspection as outlined in NFPA 25 should be completed before considering sprinklers for testing.  Any sprinkler that shows signs of the following shall be replaced:

  • Leakage
  • Corrosion detrimental to sprinkler performance
  • Physical damage
  • Loss of fluid in the glass bulb heat-responsive element
  • Loading detrimental to sprinkler performance
  • Paint other than that applied by the sprinkler manufacturer

If you have any questions regarding this article, please contact Dyne Fire Protection Labs at or (800) 632-2304.

©Dyne Fire Protection Labs 2021