Field Testing Procedures and Troubleshooting
Test fundamentals
Testing verifies that check valves hold and that the relief valve opens at the correct differential. Use a calibrated differential test kit, record gauge readings, and follow the manufacturer's procedure. The three classic checks on an RP are: check valve 1 holds against reverse flow, check valve 2 holds, and the relief valve opens when the differential across check 1 falls to the specified threshold (commonly around 2 psi, but confirm the listing).
Typical sequence
- Flush and stabilize flow.
- Test check 1 for tightness.
- Test check 2 for tightness.
- Test relief valve opening point.
- Record all readings, device make, model, size, serial number, and tester certification.
Troubleshooting
- Relief valve drips continuously: debris on check 1 seat, failed check 1, or thermal expansion.
- Relief discharges during test only: normal if within specification; if outside, check 1 is leaking.
- Check 2 fails: debris or worn seat; disassemble and clean, replace parts as needed.
- Gauge readings erratic: air in the line, faulty gauge, or unstable supply pressure.
Traps
- Passing a device without testing all three functions.
- Using an uncalibrated gauge.
- Confusing a normal relief discharge during testing with a failure.
- Failing to record serial numbers, which invalidates the report.
Rule of thumb
Test in order, record everything, and never sign off on a device you could not fully exercise. A report without readings and serial numbers is not a valid test report.
Worked example
An RP relief valve drips at rest. The tester isolates the device and finds check 1 does not hold. The fix is to clean or replace check 1, not to adjust the relief valve spring.