By Grant Lobdell

The 2017 Edition of National Fire Protection Association (NFPA) 25 “The Standard for the Inspection, Testing, and Maintenance of Water Based Systems” states in section, “A representative sample of sprinklers for testing shall consist of a minimum of not less than four sprinklers or 1 percent of the number of sprinklers per individual sprinkler sample, whichever is greater.”  Furthermore, some suggested guidance on what defines a sprinkler sample is given in the explanatory section of the Annex of NFPA 25 where A. states, “Within an environment, similar sidewall, upright, and pendent sprinklers produced by the same manufacturer could be considered part of the same sample, but additional sprinklers would be included within the sample if produced by different manufacturers.”  

This wording would suggest that sprinklers that differ in design other than orientation and sprinklers from different manufacturers should be represented in your sampling in an environment.  For instance, let’s look at a building with 400 sprinklers.  The sprinklers in the office area might be a different type than the sprinklers in the warehouse area.  Note: NFPA seems to be saying a difference in just orientation of a sprinkler of the same model isn’t to be considered a different sprinkler type.  If you were to sample 4 sprinklers from that 400 sprinkler building, both types should be included in your sample. 

To accommodate all the different types of sprinklers represented, you may want to sample more than 4 sprinklers or 1%.  For example, if there are 5 different types of sprinklers in that same 400 sprinkler building, you may want to send in one of each type, which would make for 5 sprinklers instead of the minimum of 4. This would be a more representative sample and is recommended because each type could age or become affected by the environment differently.   Keep in mind though that the Annex is suggested material and not enforceable unless adopted as such in your area.

While sampling within an area is clearly defined, NFPA 25 leaves defining the area up to the building owner.  The building owner may feel the warehouse and office are in the same type of environment and therefore will be sampled together, or the building owner may feel the 2nd and 3rd floors of their building are completely different and are therefore treated as separate sampling areas.  It is too difficult to define a sampling environment that would fit all types of buildings. 

A “sprinkler system” is clearly defined in the 2017 edition of NFPA 25. So while it would be easy to require each sprinkler system be sampled, rather than an environment, this could possibly restrict the building owner. To get a better sense of the impact of this, let’s look at a 20-story building with 200 sprinklers on each floor that are the same type and made by the same manufacturer.  You could define the sample environment by floor or you could define the whole building as the environment. Note that there are additional ways that you could separate the building.  In the first example, you would be required to take 4 sprinklers from each floor or 80 sprinklers in total.  In the second example, you would be required to take 1% of the whole building or just 40 sprinklers in total. 

However, you’ll need to consider what NFPA 25 says about sprinklers failing to meet performance requirements: “Where one sprinkler within a representative sample fails to meet the test requirements, all sprinklers within the area represented by that sample shall be replaced.”  In the first example, if you had one sprinkler fail on the 1st floor, you would need to replace only that floor’s sprinklers since each floor was represented in a different sampling.  In the second example, one sprinkler failure on the 1st floor would require sprinkler replacement for the whole building.

Let’s look at combining all of these NFPA requirements and suggestions into a more complicated example.  Let’s say we have a 4 story building with 100 sprinklers on each floor:

  • On the 1st floor, there is an office, warehouse, and pool area that each have different sprinklers
  • The 2nd floor is all conference room areas with a different type of sprinkler
  • The 3rd and 4th floors are all living spaces with yet another type of sprinkler 

That is a total of 400 sprinklers in the building with 5 different sprinkler types.  What is required by NFPA for sprinkler sampling and what is suggested? 

The only NFPA 25 requirement is that you must send in 4 or 1% of the sprinklers sampled, whichever is greater.  The building owner could define the sampling environment as the building.  This would mean they need to send in 4 sprinklers in total.  However, it is suggested that since there are 5 different types of sprinklers, they send in one of each type for a total of 5 sprinklers.  However, due to the different environments in the building, there is yet another suggested sample size that could be done.  

Due to the possible harsher environments of the warehouse and pool area, those might be sampled on their own.  The office, conference, and living areas could still be considered the same sample if the owner feels they are in similar environments.  In this example, the building owner could send in 4 sprinklers from the warehouse area, 4 from the pool area, and 4 from the office/conference/living area (at least 1 of each sprinkler type represented in the sample).  This would be a total of 12 sprinklers.  Again, the benefit of this sampling is that if a sprinkler should fail in the pool or warehouse area due to the harsh conditions, you would only be required to replace the area represented by the failure(s).  

Furthermore, the building owner could further break up the office, conference, and living area environments into different samplings which would result in a total of 20 total sprinkler samples.  While this involves even more sprinklers being sampled initially, it could further reduce the number of sprinklers that might need to be replaced.  As you can see, there are a number of sampling choices available to the building owner.  A discussion between the building owner and contractor should take place to outline the benefits and draw backs of different sampling sizes and areas.  Consider smaller sample sizes for harsh environments where failures could be more likely. 

 Ultimately, it will be the building owner’s responsibility for determining the sampling environment(s).  As always, consider local requirements that could be enforced in addition to NFPA requirements.  Also note that the Authority Having Jurisdiction (AHJ) for your building may have additional or different requirements as well.  For more information, contact NFPA directly at or Dyne Fire Protection Labs at or (800) 632-2304.            

Note: Any opinions expressed in this correspondence are the personal opinion of the author and do not necessarily represent the official position of the NFPA or its Technical Committees. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services.