NFPA 20 - 4.32.4.3

[Willie Delim]

Hi - NFPA 20 - 4.32.4.3 States that "There shall be two inspection test valves attached to the pressure sensing line that shall consist of a tee, a valve, a second tee with the branch plugged, and a second valve.[See Figure A.4.32(a)and Figure A/4/32(b)], Figure A.4.32(a) shows two inspection test valves in the illustration but there is also a label " Test connection A or B".
Question: Do we need two inspection test valves on a pressure sensing line or one is acceptable?

 

[skdesigner]

I assume your question is about whether you need two sets of test valves, as shown in the annex of NFPA 20. A single set of valves is acceptable. The reason being that water is more or less incompressible, and the sensing line holds a very small volume of water. Opening a valve installed anywhere on the sensing line is going to have the desired effect of lowering the pressure at the controller immediately.

 

[Willie Delim]

Hi skdesigner, I agree with your opinion, but NFPA 20 - 4.32.4.3 states "Shall" have two(2) inspection test valves, - "Shall" denotes mandatory.