Does NFPA address the range of the test gauges? I have a contractor that wants to perform a 200 psi test using 200 psi gauges. ASME requires that the gauge be a minimum of 1.5 times the test pressure but I am not familiar with NFPA or its requirements.
I do not know of anything in NFPA for the pressure range of "test guages", but according to NFPA-13 2002 edition, 8.16.3.3 the required pressure guages shall be listed and shall have a maximum limit not less than twice the normal system working pressure at the point where installed.
I always use a 300 psi guage like the ones that are on the system riser. Does not sound too safe using a 200 psi guage for a 200 psi test.
When they do their hydro test check the guages on the riser if the piping is connected to the riser.
I once attended a class on instrument calibration. Some important points were
1. just because it is digital doesn't mean it is more accurate than other styles of instuments and
2. instruments are most accurate in the middle third of their range.