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NFPA 13 Minimum pipe size for pilot line detectors?

NFPA 13 Minimum pipe size for pilot line detectors?

(OP)
Dear Forum,

I have previously used 1" pipe as pipe size for pilot line detector lines for deluge systems. However in figures for deluge systems of cooling towers in the Annex (A.22.21.2.1 thru 22.21.2.3), it indicates 1/2" pilot line.

Has anyone seen anything that would specify NFPA 13 minimum pipe size for pilot line detectors?

RE: NFPA 13 Minimum pipe size for pilot line detectors?

In the 1000's of deluge systems I have inspected they all used 1/2" pipe.

RE: NFPA 13 Minimum pipe size for pilot line detectors?

(OP)
Interesting LCREP. Thank you. Seems I've been oversizing.
A bit strange that it isn't specified anywhere no?

RE: NFPA 13 Minimum pipe size for pilot line detectors?

All that pipe is doing is holding air, making it bigger does not help. Air empties from the pipe deluge valve trips, simple as that.

RE: NFPA 13 Minimum pipe size for pilot line detectors?

(OP)
Thank you LCREP and Travis.

Concensus certainly seems to 1/2" is the norm which matches the diagrams in NFPA so it's 1/2" from here on ;)

Makes sense enough LCREP that it is just holding air, etc. but similarly to Travis I was taught one way many moons ago and just figured that it was subject to the minimum of 1" minimum for steel pipe as required for sprinkler system pipe. I am wiser now.

Thank you both very much for your insight.

RE: NFPA 13 Minimum pipe size for pilot line detectors?

[Was just curious, are pilot lines now always "air"?]

RE: NFPA 13 Minimum pipe size for pilot line detectors?

(OP)
That's all that I've seen & heard of rconner.

RE: NFPA 13 Minimum pipe size for pilot line detectors?

Water or air, most are air given the problems with freezing of the water in cold climates. But in the south, were it does not freeze, they use water, no air compressor needed.

RE: NFPA 13 Minimum pipe size for pilot line detectors?

While it is going off on at least a little more tangent, was further curious is there any other functional difference between the air and water e.g. in response time to release a clapper, and the needed "deluge" etc?

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