As a contractor we have a different understanding between the consultant about NFPA 14,7.2 pressure limitation.We understand that the valves & fittings pressure level in standpipe system meet the working pressure, but They demand firefighting valves should be 350 Psi.
Here is the description:
Please note that the term working pressure mentioned in NFPA 13 which is the SCR(site clarification request) is referring to is not meant by the pump head itself but shall be the pump churn pressure, refer to below NFPA 13 clause 10.10.2.2 along with the related illustration in the relevant annex, noting that churn pressure is around 110 to 115 % maximum based on most of fire pumps actual curves,also the same of the above is applicable for standpipe system as explained in NFPA 14. Accordingly firefighting valves shall be rated to 350 PSI. In light of the above contractor shall follow project specifications and to investigate/explore the market and other suppliers providing UL/FM approved high pressure valves and to be based on his own verified fire pump head calculations, noting that 350 Psi is in line with NFPA requirements as explained and as clearly mentioned in NFPA 14, A.7.2.
How to prove their understanding is wrong?