by Grant Lobdell, President, Dyne Fire Protection Labs

According to the current, 2023 edition of NFPA 25, the Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, sprinklers shall be inspected from the floor level annually, and any sprinkler that shows signs of the any of the following shall be replaced:

  1.  Leakage
  2. Corrosion detrimental to sprinkler performance
  3. Physical damage
  4. Loss of fluid in the glass bulb heat-responsive element
  5. Loading detrimental to sprinkler performance*
  6. Paint, other than that applied by the sprinkler manufacturer, detrimental to sprinkler performance

Note the phrase “detrimental to sprinkler performance”, which has always been associated with the evaluation of corrosion and loading, has now been added to the evaluation of non-manufacturer applied paint.

Corrosion, loading, and/or paint found on the water seal or activation mechanism could delay or even prevent a sprinkler’s release, whereas corrosion, loading, and/or paint found in the deflector could impact the sprinkler’s water distribution pattern.  Signs of corrosion, loading, and/or paint in these areas should be considered detrimental and those sprinklers that show these signs shall be replaced.

*Note that, according to the annex of NFPA 25, loaded sprinklers can be cleaned with compressed air or a vacuum provided such equipment does not touch the sprinkler, potentially removing the detrimental loading and therefore avoiding the need for replacement.  Great care should always be taken to not damage the sprinkler which can lead to premature activation and significant water damage.

Corrosion, loading, and/or paint simply found on the frame such that it does not impact the sprinkler’s operation may not be considered detrimental, and, if so, sprinklers that show these signs do not need to be replaced according to the most recent edition.  Previous editions of NFPA 25, however, which your jurisdiction is most likely still referencing, required the replacement of sprinkler with signs of non-manufacturer applied paint regardless of where that paint is located/if it would be detrimental to the operation of the sprinkler.

If there is ever any doubt whether corrosion, loading and/or paint may be determinantal, the sprinklers can always be tested by an approved testing laboratory, such as Dyne Fire Protection Labs, to remove any ambiguity.  If the sprinkler(s) in question pass the non-routine field service test as described in NFPA 25, the corrosion, loading, and/or paint discovered would not be considered detrimental and replacement would not be required.

Examples of sprinklers with detrimental corrosion, loading, and/or paint, as confirmed by the field service test at Dyne Fire Protection Labs, can be found on our website for your reference.

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

©Dyne Fire Protection Labs 2024