Question 1

An RPZ assembly is continuously discharging water from the relief valve during normal system operation. What is the most likely cause?

Accepted Answer

Continuous discharge indicates that the relief valve is opening because the pressure between the checks exceeds the setpoint. This occurs when both checks are leaking, preventing the system from reaching equilibrium.

Question 2

An RPZ assembly is intermittently dripping from the relief valve. What might this indicate?

Accepted Answer

Intermittent or occasional drips suggest minor leakage from Check #2, which is often within acceptable limits during testing. Continuous discharge would indicate a more serious problem.

Question 3

When testing an RPZ assembly, the gauge reading at Check #1 is 0 PSI. What does this indicate?

Accepted Answer

A 0 PSI reading at Check #1 means the first check is not holding any differential pressure, indicating complete valve failure. The assembly must fail the test and be repaired.

Question 4

During RPZ testing, the gauge at Check #2 is fluctuating between 2 PSI and 4 PSI. What is the likely cause?

Accepted Answer

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.

Question 5

The tester cannot achieve the initial bleed to bring both downstream and upstream gauges to 0 PSI on an RPZ. What is the most likely cause?

Accepted Answer

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.

Question 6

A backflow prevention assembly passes the field test with acceptable pressure readings, but the property owner reports contaminated water. What is the next step?

Accepted Answer

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.

Question 7

During testing, a check valve reading shows 4.8 PSI but the spec minimum is 4.5 PSI. The gauge has ±0.1 PSI accuracy. Is this a pass or fail?

Accepted Answer

At 4.8 PSI with ±0.1 PSI accuracy, the true value could be 4.7-4.9 PSI. Since the minimum is 4.5 PSI, this is above minimum but within margin of error. Retest or use more precise gauges.

Question 8

A Double Check (DC) valve passes Check #1 but fails Check #2. What is the appropriate action?

Accepted Answer

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

Question 9

A PVB assembly's air inlet valve won't open during testing. What is the likely cause?

Accepted Answer

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.

Question 10

The system pressure at the backflow assembly test location is 25 PSI, but the device is designed for 30-80 PSI minimum operating pressure. Can testing proceed?

Accepted Answer

Backflow devices have minimum operating pressures specified by manufacturers. Below this pressure, the device may not function properly and tests are invalid. Pressure must be brought within operating range.

Question 11

During testing, the tester finds debris accumulated in the test cocks, preventing accurate pressure readings. What is the correct action?

Accepted Answer

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.

Question 12

A test hose connection is leaking during the test procedure, causing pressure readings to drop. What should the tester do?

Accepted Answer

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.

Question 13

Upon arrival to test a backflow device, the tester finds it is installed in a crawl space, buried under insulation and pipe wrap, making it inaccessible. What is the appropriate action?

Accepted Answer

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.

Question 14

An RPZ relief valve discharged continuously for a week before the tester arrived. What does this indicate?

Accepted Answer

Continuous discharge over an extended period indicates chronic check valve failure. The assembly is not providing protection and must be repaired immediately.

Question 15

A visual inspection reveals corrosion on the backflow assembly body and test cocks. The assembly tests with acceptable pressure readings. What is the appropriate recommendation?

Accepted Answer

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

Question 16

When testing, the upstream gauge reads 30 PSI and the Check #1 gauge reads 29 PSI. What does this indicate?

Accepted Answer

A 1 PSI differential between upstream and Check #1 indicates proper check valve operation. The check is holding pressure as expected and has passed this portion of the test.

Question 17

A relief valve begins opening slightly when the RPZ sees a 3 PSI differential between the checks. The specification calls for a 2.5 PSI opening pressure minimum. Is this acceptable?

Accepted Answer

A relief valve opening slightly above the minimum specification (3 PSI vs. 2.5 PSI minimum) is typically within acceptable tolerances. The valve is functioning correctly.

Question 18

Check valve seats appear to have mineral buildup but pressure readings are within acceptable limits. What action should be taken?

Accepted Answer

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

Question 19

When attempting to test a backflow device, the test cocks have no pressure; opening them yields no water flow. What is the likely cause?

Accepted Answer

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.

Question 20

An assembly shows a steady pressure reading of 5 PSI at Check #1, but the specification minimum is 4.5 PSI and maximum is 6.0 PSI. Is this acceptable?

Accepted Answer

A 5 PSI reading falls squarely within the 4.5-6.0 PSI specification range. This indicates the check is functioning properly and has passed the test.

Question 21

A Double Check assembly passes both check valves but the relief valve is found to be stuck open. What is the appropriate action?

Accepted Answer

The relief valve is a critical safety component. A stuck-open relief compromises the entire assembly regardless of check valve performance. The assembly must fail and be repaired.

Question 22

When testing, the downstream gauge immediately reads high pressure instead of bleeding down to 0 PSI. What is blocking the downstream bleed?

Accepted Answer

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.

Question 23

An RPZ assembly shows Check #1 at 4 PSI and Check #2 at 2 PSI. The specification requires Check #1 to be 0.5-3 PSI above Check #2. Is this acceptable?

Accepted Answer

Check #1 is 2 PSI above Check #2 (4-2=2), which falls within the 0.5-3 PSI differential requirement. This is acceptable and indicates proper operation.

Question 24

A backflow assembly installed 10 years ago is visually deteriorated with peeling paint and surface rust, but passes all pressure tests. What is recommended?

Accepted Answer

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.

Question 25

When testing a device, water is visibly leaking from the connection between the device body and a test cock. What should the tester do?

Accepted Answer

A leaking connection compromises the assembly's integrity and makes accurate testing impossible. The device must fail and be repaired by a qualified technician.

Question 26

A PVB assembly exhibits a small amount of water dripping from its air inlet continuously. What does this indicate?

Accepted Answer

Minor dripping from the air inlet may be acceptable during normal operation, but it indicates some wear. The device should be monitored, and replacement should be planned.

Question 27

During testing, the tester discovers the backflow assembly does not have serial number identification. What action is required?

Accepted Answer

Test reports must include serial number along with make, model, and size. Without proper identification, the test report cannot be completed, and the device cannot be certified.

Question 28

An RPZ assembly passes the test, but upon questioning the property manager reveals the relief valve has been discharging continuously for several weeks. What should the tester recommend?

Accepted Answer

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.

Question 29

When testing a new installation, the backflow device cannot be located despite being listed on the construction plans. What is the appropriate action?

Accepted Answer

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.

Question 30

During an RPZ test, Check #1 holds 5 PSI but Check #2 reads 0 PSI and will not hold any downstream pressure. What should the tester conclude?

Accepted Answer

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.

Field Troubleshooting Practice Questions

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