Field Test Procedures and Test Equipment
Test discipline
Field testing proves that an assembly performs as designed under controlled conditions. Before connecting hoses, inspect the assembly, confirm flow direction, identify test cocks, and verify the differential pressure gauge is calibrated, undamaged, and zeroed. Use clean hoses and avoid cross-contamination between potable and nonpotable ports. Record supply pressure, downstream pressure, differential readings, check-valve hold values, and relief-valve opening and closing behavior.
For an RPZ, test both check valves and the differential relief valve. Confirm the relief valve opens at the required differential and closes without continuous discharge. For a DCVA, test both check valves for tightness. For a PVB, test the air-inlet opening and the check valve. An AVB is generally not field-tested because it has no test cocks; verify installation, critical level, and absence of continuous pressure instead.
Traps: reversed hose connections, a gauge that does not return to zero, leaking test cocks, and testing an assembly while it is dirty or partially isolated. Another trap is recording a “pass” without noting gauge identification or calibration date. Follow the adopted standard and manufacturer instructions when values differ.
Worked example
A gauge reads 1.0 psi before any pressure is applied. Do not subtract that value from every reading; zero or replace the gauge, then retest. Rule of thumb: a test is only as valid as the gauge, the hose connections, and the recorded conditions.