From NFSA’s Tech Notes #367 February 14, 2017
Is there a standard for replacing sprinklers after a fire? How many sprinklers would have to be replaced beyond the limits of the fire area?
Answer: NFPA 25 contains annex language addressing this situation. Annex section A.5.2 of the 2017 edition of NFPA 25 (similar language in earlier editions) reads as follows:
“A.5.2 The provisions of the standard are intended to apply to routine inspections. In the event of a fire, a post-fire inspection should be made of all sprinklers within the fire area. In situations where the fire was quickly controlled or extinguished by one or two sprinklers, it might be necessary only to replace the activated sprinklers. Care should be taken that the replacement sprinklers are of the same make and model or that they have compatible performance characteristics (see 22.214.171.124). Soot-covered sprinklers should be replaced because deposits can result in corrosion of operating parts. In the event of a substantial fire, special consideration should be given to replacing the first ring of sprinklers surrounding the operated sprinklers because of the potential for excessive thermal exposure, which could weaken the response mechanisms.”
Each fire event is different and it is important to perform a thorough inspection of the premises that were subject to a fire event before determining which sprinklers must be replaced. Any sprinklers that are loaded or covered with soot would need to be replaced. Also, great care must be taken to ensure that sprinklers that have been exposed to elevated temperatures are replaced. Even if the sprinklers did not activate, if they were subject to elevated temperatures, the operating elements could be weakened and the sprinkler may not operate properly.