Field Troubleshooting Practice Questions

Explanation: Fluctuating pressure readings typically indicate debris under the check disc preventing a full seal, or loose test hose connections allowing air leaks. Clean the check or tighten connections.

Explanation: If the downstream shutoff valve is leaking, the downstream gauge will not reach 0 PSI during the bleed procedure. The valve must be repaired or replaced.

Explanation: A passed assembly does not guarantee that contamination is impossible—other plumbing issues, cross-connections, or actual backflow sources may exist. Investigation is needed to locate the source.

Explanation: Readings are judged as read, with no gauge-tolerance subtraction. Check #1 must be ≥5.0 PSID and above the relief opening point, and 5.0 PSID meets both. As with a DC check reading exactly 1.0 PSID, a reading at the minimum passes.

Explanation: Both checks must pass independently. A failed Check #2 means the assembly cannot provide adequate protection and must be removed from service and repaired.

Explanation: If the air inlet won't open, debris or corrosion likely prevents operation. The valve must be cleaned or replaced; without air inlet function, backflow protection is compromised.

Explanation: Check valve differentials come from spring loading, not supply pressure, so a steady 25 PSI supply still allows a valid test. Each DC check must hold at least 1.0 PSID. A steady supply matters more than a high one.

Explanation: Test cocks must be clean to provide accurate pressure readings. Debris can cause false readings. The tester should clean the cocks before proceeding with testing.

Explanation: Leaking connections compromise test accuracy and must be repaired before proceeding. The tester should fix the leak, re-establish pressure, and repeat the testing procedure.

Explanation: Backflow devices must be in accessible locations for testing and maintenance. An inaccessible device violates installation codes and must be relocated. The water purveyor must be notified.

Explanation: Continuous discharge over an extended period usually means check #1 (or the relief valve seat) is fouled and leaking, so the zone keeps rising to the relief opening point. The assembly should be repaired and retested promptly.

Explanation: While current test results may be acceptable, corrosion indicates age and material degradation. The device should be monitored closely and replaced before failure occurs.

Explanation: A 1.0 PSID differential across check #1 meets the DC minimum of at least 1.0 PSID, and readings are judged as read. Check #1 passes this portion of the test.

Explanation: The relief valve must open with a supply-to-zone differential of at least 2.0 PSID. Opening at 3.0 PSID passes. Check #1 must then hold at least 5.0 PSID and be above 3.0 PSID.

Explanation: Mineral deposits on check seats reduce their service life and may eventually cause failure. Preventive cleaning or replacement planning is appropriate to maintain protection.

Explanation: No pressure at the test cocks typically means the upstream water supply is shut off at the meter or by an isolation valve. The tester must verify the upstream supply is on before proceeding.

Explanation: An RP check #1 passes when it holds at least 5.0 PSID and is above the relief valve opening point. At 5.4 PSID with a 2.5 PSID opening point, it meets both criteria. There is no maximum.

Explanation: The relief valve is a critical part of an RP assembly. If it is stuck open, the assembly fails no matter how the checks performed, and it must be repaired and retested.

Explanation: If downstream pressure won't bleed to zero, the downstream shutoff valve is likely partially closed or leaking backwards. This isolation valve must be opened fully or repaired.

Explanation: Check #1 on an RP must hold at least 5.0 PSID and also be above the relief opening point. At 4.0 PSID, check #1 is above the 2.8 PSID opening point but below the 5.0 PSID minimum, so the assembly fails and must be repaired and retested.

Explanation: While current performance may be acceptable, significant age and visible deterioration indicate the assembly is reaching end-of-life. Replacement should be planned to avoid unexpected failure.

Explanation: A leaking test cock connection compromises the assembly and the accuracy of the test. Many programs commonly require the tester to document the leak, record the assembly as failed, and notify the water purveyor until it is repaired and retested. Local requirements vary.

Explanation: Continuous dripping from a PVB air inlet means the air inlet seat, or a leaking check seat, is not sealing. The PVB should be repaired (cleaned or rebuilt) and retested: the air inlet must open at ≥1.0 psi and fully, and the check must hold ≥1.0 psid. A PVB has no relief valve.

Explanation: The tester should still test the assembly and record make, model, size and location. On the report, note that no serial number was found and report it to the water purveyor or program administrator, who decides on any follow-up.

Explanation: Continuous relief discharge over weeks indicates chronic check valve failure. Even though it passed today's test, the device is not providing protection and needs immediate repair.

Explanation: The specific device on the approved plans must be located and tested. If not found, verification is needed that it was installed. Testing cannot proceed without locating the actual device.

Explanation: Check #2 must hold its own differential pressure. A 0 PSI reading indicates complete failure of the second check. The assembly cannot provide backflow protection and must fail the test.