By Alyssa Dunn, General Manager, Dyne Fire Protection Labs
In our December 2025 newsletter, we discussed defining your sample area. Once your sample area has been defined, a representative sample of the sprinklers in the sample area should be sampled and submitted to the laboratory for field service testing. According to NFPA 25, the Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, a sample size should include a minimum of four or 1% of the number of sprinklers per sample area, whichever is greater.
5.3.1.2 A representative sample of sprinklers for testing in accordance with 5.3.1.1 shall consist of either a minimum of four sprinklers or 1 percent of the number of sprinklers per sample area, whichever is greater.
The sprinklers in the representative sample should be selected somewhat randomly, but each sprinkler type and manufacturer within the sample area shall be represented in the sample (Section 5.3.1.2.1). Sprinklers replaced at prior testing intervals shall not be included in the samples tested (Section 5.3.1.2).
5.3.1.2.1 Each sprinkler type and manufacturer in the sample area shall be represented in the sample.
5.3.1.2.2 Sprinklers tested shall not include any sprinklers that were replaced at prior testing intervals.
If I have different types of sprinklers in my sample area, how many of each do I need to send in for testing?
A representative sample should include one of each type of sprinkler. For example, if your defined sample area is an office space with 4 different types of sprinklers – the representative sample should include one of each type. If there were only 2 different types of sprinklers – the representative sample should include at least one of each type, but a total of 4 or 1% of the total number of sprinklers is still needed per NFPA 25.
Do I need a separate sample area for each type of sprinkler?
NFPA 25 does not define how sample areas should be determined. If you’ve defined your sample area by environment, a representative sample should include one of each type of sprinkler. However, if you’ve defined your sample area by sprinkler type, you would need to sample 4 or 1% of the sprinklers of that type.
What is the definition of different types of sprinklers?
Sprinklers could be considered different types if they differ in temperature rating, release mechanism type, water seal configuration, manufacturer, etc. However, sprinklers of the same type and manufacturer that only differ in orientation (i.e. pendent, upright, sidewall) are considered the same type for the purpose of sampling. One of each orientation is not needed for sampling unless the sprinklers differ in type or manufacturer.
One of my sprinklers failed, what do I replace?
5.3.1.3 Where one sprinkler within a representative sample fails to meet the test requirement, all sprinklers within the area represented by that sample shall be replaced.
A common misconception is that the sprinklers of the specific type that failed need to be replaced, but that is not the case. Replacement depends on how the sample area was defined. In the example of the office space with 4 different types of sprinklers, if one of the sprinklers fails, all of the sprinklers in the office space should be replaced – not just the type that failed.
Questions? Contact us today by calling (800) 632-2304 or emailing dyne.lab@nfpaglobal.com.
Questions? Contact us today by calling (800) 632-2304 or emailing dyne.lab@nfpaglobal.com.
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