10 psi per week for loss of air in a dry system? 1

[ContractorDave]

I'm looking at an ASFA report for inspection of dry systems where Leaks resulting in air pressure losses greater than 10 psi / week shall (be) located and repaired. I do not see this stated as such anywhere in NFPA 25.

5.2.4.1 states in part: ...to ensure that normal air and water pressures are being maintained. ...A little on the "let's cover all the bases with one broad statement" side of things.

If you take NFPA 13s Acceptance Test figure for pneumatic testing where you establish 40 psi and test without a loss of greater than 1 1/2 psi over 24 hours - extrapolating from this you can come up with "a loss of 10.5 psi per week is unacceptable".

On a system employing a Vicatualic 768 where shop air is used, checking the gauges on a weekly basis may never tell you anything anyways. The only way to tell if this system is losing air is to isolate it from it's air supply for a while.


Thoughts?

Regards
Dave

 

[skdesigner]

I also couldn't find the 10 psi requirement.

NFPA 25 2007 13.4.4.2.9 Dry pipe systems shall be tested once every three years for air leakage, using one of the following test methods:

(1) A pressure test at 40 psi for 2 hours. The system shall be permitted to lose up to 3 psi during the duration of the test. Air leaks shall be addressed if the system loses more than 3 psi during this test.

(2) With the system at normal pressure, shut off the air source (compressor or shop air) for 4 hours. If the low air pressure alarm goes off within this period, the air leaks shall be addressed.

The latter seems like it would deal with your particular problem (shop air).

 

[skdesigner]

make that NFPA 25 *2008* ed.

 

[ContractorDave]

Thanks skdesigner

It stays the same for the 2011 edition as well.

Regards
Dave

 

[NJ1]

Very simple answer. Just remember that NFPA is designed to cross reference chapters within the standard and or other standards in order to find your answer.

NFPA 25-2002
Chapter 12
Valves, Valve Components, and Trim
12.4.4.3.1

I hope this helps

 

[NJ1]

Very simple answer. Just remember that NFPA is designed to cross reference chapters within the standard and or other standards in order to find your answer.

NFPA 25-2002
Chapter 12
Valves, Valve Components, and Trim
12.4.4.3.1

I hope this helps

 

[chicopee]

As to the cause of the air leak, check the water seal at the clapper of the dry sprinkler alarm check valve as a possible solution.

 

[ContractorDave]

Thanks chicopee

We're going to do hydrostatic testing starting at supply pressures and then ramping it up from there (sometimes grooved couplings won't leak at higher pressures).

Regards
Dave