By John Langteau  

At Dyne Fire Protection Labs, we get many questions from customers who are sending in sprinklers for testing about what’s allowable/acceptable with sprinklers. This article looks to answer the more common questions, using NFPA standards and our own experiences.

Can a loaded sprinkler be cleaned?

According to the current, 2017 edition of NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, sprinklers that have a light coating of dust or debris may be cleaned using compressed air and or a vacuum. A blast of compressed air or vacuum may be used to remove the dust or debris while the sprinkler remains in place. While the cleaning is taking place it is important to not touch or damage the release mechanism of the sprinkler, whether it is a glass bulb or a fusible link. At no time should any chemical cleaning product be used on the sprinkler either liquid or aerosol. It is recommended that any sprinkler that cannot be cleared of detrimental dust or debris shall be replaced (Figure 1).

Figure 1

Is paint allowed on a sprinkler?

According to the current, 2019 edition of NFPA 13, Standard for the Instillation of Sprinkler Systems, section stipulates that sprinklers shall only be painted by the sprinkler manufacturer. The sprinkler manufacturer is allowed to paint sprinkler pieces before assembly. Depending on where the paint is located, paint applied after manufacturing (after the sprinkler is put together) could insulate the release mechanism, bind parts that are supposed to be free moving upon release, and/or impact the water distribution patter. As a result, according to the current, 2017 edition of NFPA 25, during the annual floor level inspection, a sprinkler that features paint other than that applied by the manufacturer shall be replaced according to section (Figure 2). This includes paint applied to cover plates. It is possible that the paint applied to the cover plate seeps behind the edges of the plate and binds or insolates the solder release tabs on the plate.

How much corrosion is allowed or acceptable?

According to the current, 2017 edition of NFPA 25, the criteria for replacement is based on whether or not the corrosion is detrimental to the sprinkler performance. This allows some gray area when determining what is simply cosmetic vs. what is detrimental. Excessive corrosion on a soldered release mechanism or water seal can fuse the release mechanism together or fuse the water seal to the frame respectively thus preventing release. Figure 3 shows examples of heavily corroded water seals that failed to release during field service testing.

For more examples of detrimental corrosion, please review Examples of Detrimental Loading and/or Corrosion published by Dyne Fire Protection Labs on April 2018.  For information about getting kits, sending sprinklers to Dyne for testing, what happens during testing, etc, our Sprinkler FAQ is available on our website as a resource for you.

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