NFPA 13 Minimum pipe size for pilot line detectors? 2

[Cidona]

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?

 

[LCREP]

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

 

[Cidona]

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

 

[TravisMack]

Check the material data sheets for the systems. It may be in there. I have always used 1/2" pilot line piping as that is how I was taught many many moons ago.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

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[LCREP]

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.

 

[Cidona]

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.

 

[rconner]

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

 

[Cidona]

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

 

[LCREP]

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.

 

[rconner]

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?