The 2017 Edition of NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems states in 5.2.1.1.1 that “any sprinkler that shows signs of loading and/or corrosion detrimental to the sprinkler performance shall be replaced”.  By simply looking at the sprinkler, it can be difficult to know when loading and/or corrosion is detrimental to the performance. To help those in the field make this call, this document has been put together with some real-life examples of loaded and/or corroded sprinklers that have response times outside the acceptable range.  Generally, loading will increase response time due to its insulating effect on the release mechanism whereas corrosion will hold the water seal or release mechanism together longer than desired or, in some cases, prevent release entirely. 

The required response times listed are based on the RTI calculation as
defined in UL 199 and Dyne’s plunge oven test conditions.

Standard Response Sprinklers

Required Response Time: 27.3 - 129 s

Response Time: 132.1 s FAIL

Required Response Time: 27.3 – 129 s

Response Time: 131.3 s FAIL

Required Response Time: 27.3 – 129 s

Response Time: 136.3 s FAIL

Required Response Time: 28.8 – 132.1 s

Response Time: 137.6 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: 142.1 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: 145.1 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: 150.2 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: 152.0 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: 153.7 s FAIL

Required Response Time: 27.3 – 129 s

Response Time: 160.0 s FAIL

Required Response Time: 27.3 – 129 s

Response Time: 166.6 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: 171.6 s FAIL

Required Response Time: 29.5 – 138.9 s

Response Time: Did Not Release FAIL

Fast Response Sprinklers

In the fast response sprinkler pictures, please note that it may take much less loading and/or corrosion to move the response time out of the acceptable range than for a standard response sprinkler.  This is because a fast response sprinkler is required to go off much more quickly and within a tighter window.  Whereas a standard response sprinkler can have an RTI value between 80 (meters-seconds)1/2 and 350 (meters-seconds)1/2, a fast response sprinkler must have an RTI below 50 (meters-seconds)1/2.

Required Response Time: 0 – 17.1 s

Response Time: 19.5 s FAIL

Required Response Time: 0 – 18.4 s

Response Time: 25.6 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 24.4 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 23.3 s FAIL

Required Response Time: 0 – 19.8 s

Response Time: 21.3 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 21.0 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 20.8 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 20.6 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 17.3 s FAIL

Required Response Time: 0 – 17.1 s

Response Time: 17.3 s FAIL

 

When considering whether to replace loaded sprinklers specifically, Section A.5.2.1.1 of the 2017 Edition of NFPA 25 states, “In lieu of replacing sprinklers that are loaded with a coating of dust, it is permitted to clean sprinklers with compressed air or a vacuum, provided that the equipment does not touch the sprinkler.”  This is an option that could save some building owners from costly replacements.  However, if the loading is removed by other methods not listed, for example using some sort of brush that physically touches the release mechanism, it is possible to damage the sprinkler (or even activate it) so please be careful.

Lastly, please note the following line from NFPA 25 Annex A Section A.5.3.1.1, “If there is any question about (a sprinkler’s) continued satisfactory performance, the sprinklers should be replaced.”  This line could apply to all inspection, testing, and maintenance work.  If you are ever in doubt about a piece of equipment’s performance, whether that be because of the test results or based on your visual inspection, it is best to just replace.  As evident in the examples presented in this document, the impact of loading and corrosion is not always as apparent as we would like.  Without actually testing the sprinkler for sensitivity and functionality, err on the side of caution when making this judgment call for sprinklers on the edge.

Should you have any questions or concerns about his topic, please contact a technician from Dyne Fire Protection Labs Dyne at (800)-632-2304 or lab@dyneusa.com.

©Dyne Fire Protection Labs 2018