Troubleshooting, Repair, and Maintenance
Diagnosis
Troubleshooting starts with the symptom. Continuous relief discharge from an RPZ can mean a fouled first check, a failed relief valve seat, or debris. Intermittent discharge often indicates a thermal expansion condition or a pressure fluctuation. A check that fails to hold may have debris on the seat, a worn disc, or a broken spring. A PVB that spits water may have a failed air inlet or a check stuck open.
Know the maintenance cycle: inspect, clean, replace worn elastomers, verify spring tension, and retest after any repair. Repairs must use manufacturer-approved parts; substituting a generic spring changes the assembly's certification and is a common exam trap.
Safety and records
Isolate and depressurize before repair. After repair, a full retest is required, and the report must note the repair and the new test values. Keep parts and service records tied to the device serial number.
Worked example
An RPZ discharges continuously. The technician isolates the device, opens the first check, and finds a pebble on the seat. After cleaning and replacing the seat disc, the relief valve holds and the checks read within specification. The correct answer on an exam is not "replace the whole assembly," but "clean and retest, then document."