Question 1

When performing a Double Check Valve assembly test, what is the first step in the preliminary procedure?

Accepted Answer

The preliminary step for DC testing requires closing shutoff #2 and opening test cock #4 to bleed the system to 0 PSI, ensuring accurate baseline readings. This prevents residual pressure from affecting subsequent test results.

Question 2

What is the minimum pressure differential (PSID) required for each check valve in a Double Check Valve assembly to pass the test?

Accepted Answer

Each check valve in a DC assembly must maintain a minimum of 1.0 PSID when tested individually. This differential ensures the check valve will seat properly under normal operating conditions.

Question 3

When testing Check Valve #1 in a Double Check assembly, which test cocks are used?

Accepted Answer

Test cocks #2 and #3 isolate Check Valve #1 for testing. The high side needle valve connects to #2 (upstream of Check #1) and the low side to #3 (between Check #1 and Check #2).

Question 4

What is the purpose of bleeding air from the test hoses before recording a pressure differential reading?

Accepted Answer

Air pockets in hoses create false readings and sluggish gauge response. Bleeding air ensures the hydraulic fluid directly contacts the pressure source and gauge, providing accurate and stable PSID measurements.

Question 5

During a Double Check assembly test, the first check valve reads 0.7 PSID. What action should be taken?

Accepted Answer

A 0.7 PSID reading fails the minimum 1.0 PSID requirement for DC check valves. The assembly cannot protect against backpressure and must be removed from service and repaired or replaced.

Question 6

What is the correct position of the low side needle valve when taking a pressure differential reading?

Accepted Answer

The low side needle valve must be fully closed when recording a reading to obtain the true pressure differential across the check valve. An open low side valve will bleed pressure and provide false low readings.

Question 7

How often must a backflow prevention test kit be calibrated to ensure accuracy?

Accepted Answer

Test kits must be calibrated annually to maintain accuracy within ±0.2 PSID. Expired calibration can result in false pass/fail determinations and compromise backflow protection.

Question 8

When returning a Double Check assembly to service after testing, what must be verified?

Accepted Answer

Proper return to service requires closing all test cocks and slowly opening the downstream shutoff while checking for leaks. This confirms the assembly and shutoff valves function correctly in normal operation.

Question 9

In an RPZ assembly test, what is the minimum PSID for Check Valve #1 (inlet check)?

Accepted Answer

RPZ Check Valve #1 is the critical inlet check and must maintain a minimum of 5.0 PSID to protect against dangerous backpressure. This higher requirement reflects its critical role in zone protection.

Question 10

When testing the relief valve on an RPZ assembly, what is the minimum PSID at which it must open?

Accepted Answer

The RPZ relief valve must open at a minimum of 2.0 PSID to maintain the protected zone and protect downstream lines from excessive backpressure. This protects the integrity of the zone between check valves.

Question 11

Describe the complete sequence for testing Check Valve #1 in an RPZ assembly.

Accepted Answer

RPZ Check #1 testing requires high side on test cock #2 (upstream of check) and low side on test cock #3 (in the zone). After bleeding and closing the low side needle valve, the reading must be ≥5.0 PSID.

Question 12

During RPZ relief valve testing, what indicates the relief valve is opening correctly?

Accepted Answer

Correct relief valve operation is indicated by visible discharge (water flowing) from the relief valve's vent or drain port while observing the cracking pressure. The pressure gauge indicates the relief opening point.

Question 13

What does it mean if the relief valve in an RPZ assembly does not open during testing?

Accepted Answer

If the relief valve fails to open when test pressure is applied, the valve is either stuck or contaminated and cannot function during a real backpressure event. The assembly must be removed from service and replaced.

Question 14

When testing Check Valve #2 in an RPZ assembly, which test cocks are used and what is the minimum PSID required?

Accepted Answer

Check Valve #2 (the outlet check) is tested using test cocks #3 and #4 and must maintain a minimum of 1.0 PSID. This protects against backsiphonage on the outlet side of the assembly.

Question 15

What is the primary difference in testing procedure between a Double Check and an RPZ assembly?

Accepted Answer

RPZ testing includes an additional critical relief valve test and requires higher PSID minimums (5.0 for Check #1 vs 1.0 for DC). This reflects the RPZ's superior protection against backpressure.

Question 16

If the pressure differential gauge needle fluctuates during a test reading, what should be done?

Accepted Answer

Gauge needle fluctuation indicates air pockets in the hoses or an unstable flow. The test must be stopped, hoses bled again, and the reading retaken to ensure accuracy within ±0.2 PSID tolerance.

Question 17

What is the correct procedure for closing shutoff valve #2 during DC preliminary testing?

Accepted Answer

Shutoff #2 must be closed after the preliminary bleed procedure (opening #4 to reduce pressure to 0 PSI). Closing it at the wrong time can trap air or create inaccurate test conditions.

Question 18

During a test, the first check valve reads 1.2 PSID and the second reads 0.8 PSID. What is the status of this Double Check assembly?

Accepted Answer

Check Valve #1 passes at 1.2 PSID but Check Valve #2 fails at 0.8 PSID (below the 1.0 minimum). An assembly fails if any component fails; the entire assembly must be replaced to restore protection.

Question 19

What is the purpose of test cock #1 on a backflow prevention assembly?

Accepted Answer

Test cock #1 is located upstream of the entire assembly and allows measurement of the incoming supply pressure. This verifies that adequate test pressure is available before beginning individual check valve tests.

Question 20

An RPZ assembly test shows: Check #1 = 6.2 PSID, Relief opens at 2.1 PSID, Check #2 = 1.3 PSID. Is the assembly acceptable?

Accepted Answer

All RPZ test values meet minimums: Check #1 ≥5.0 PSID (passes), Relief ≥2.0 PSID (passes), Check #2 ≥1.0 PSID (passes). The assembly provides adequate backflow protection and is acceptable for service.

Question 21

When should test cock shutoff valve #2 be opened during the testing sequence?

Accepted Answer

Shutoff #2 is opened only after testing is complete and all test cocks are closed, allowing the assembly to return to normal service. Opening it during testing would invalidate readings.

Question 22

What does a Double Check Valve assembly protect against?

Accepted Answer

A DC assembly uses two check valves but has no relief valve to vent zone pressure. It provides strong backpressure protection through the check valves but cannot protect against backsiphonage as effectively as an RPZ.

Question 23

What should be verified after slowly opening shutoff valve #2 during return to service?

Accepted Answer

Return to service verification includes checking for any water leaking from the assembly seals or test cock connections. If an RPZ is present, any relief discharge during startup should stop once full pressure is reached.

Question 24

During testing, what does it indicate if water continuously flows from the relief valve vent even after initial pressurization?

Accepted Answer

Continuous relief flow after pressurization indicates the relief valve is not seating properly after discharge. Once the zone is charged to test pressure, the relief should stop flowing and the pressure should hold steady.

Question 25

What is the correct order of closing test cocks after completing all checks in a Double Check test?

Accepted Answer

After testing, close test cocks in reverse order: #4, #3, #2. This ensures safe depressurization and prevents sudden pressure loss. Then the shutoff valve #2 is opened to return the assembly to service.

Question 26

A Pressure Vacuum Breaker (PVB) is tested and shows the required 1.0 PSID differential. What does this indicate?

Accepted Answer

A PVB is designed to prevent backsiphonage, and a 1.0 PSID reading confirms the check valve is sealing properly. This indicates the assembly will function correctly to prevent backsiphonage events.

Question 27

When can adjustments be made to a backflow assembly during the test procedure?

Accepted Answer

No adjustments to the assembly can be made during testing. If adjustments are made, the entire test must be restarted from the beginning to ensure valid results and proper testing sequence.

Question 28

What is indicated by a stable pressure reading that remains constant when the low side needle valve is closed?

Accepted Answer

A stable, constant reading with the low side closed indicates an accurate PSID measurement with the check valve properly sealing. Any drift or decline suggests leakage or air in the hoses.

Question 29

In the preliminary procedure, why is test cock #4 opened to bleed the system to 0 PSI?

Accepted Answer

Bleeding to 0 PSI establishes a known baseline and removes any residual pressure from previous use or service. This ensures the first pressure reading is accurate and not inflated by trapped pressure.

Question 30

A technician applies 6.0 PSID of test pressure but the gauge on the low side line reads nothing. What is the most likely cause?

Accepted Answer

Zero reading on the low side typically indicates the low side needle valve is still closed or the hose is not connected to a test cock. The technician should verify the low side needle is fully open and hose connections are secure.

Question 31

After testing an RPZ assembly and finding it acceptable, what step must occur before returning it to service?

Accepted Answer

The proper return to service sequence is: disconnect test equipment, close all test cocks, slowly open shutoff #2, and verify the assembly operates without leaks and relief valve seats properly.

Question 32

What is the significance of the ±0.2 PSID accuracy specification for test kits?

Accepted Answer

The ±0.2 PSID accuracy tolerance means readings near the minimum pass/fail threshold (e.g., near 1.0 PSID for DC) could be affected by calibration drift. Close readings should be re-tested or the kit recalibrated to ensure accurate results.

Question 33

A Double Check assembly is tested with high pressure supply of 80 PSI. During Check #1 test, only 1.2 PSID registers. What does this represent?

Accepted Answer

When high side supply is 80 PSI and low side reads 78.8 PSI (or similar), the differential of 1.2 PSID across the check valve is what matters. This passes the 1.0 PSID minimum for DC check valves.

Question 34

What is the correct position of test cock shutoff valve #2 before beginning a Double Check assembly test?

Accepted Answer

Shutoff #2 must be fully closed at the start of testing to isolate the assembly from the supply pressure. This is the first step in preliminary procedure and ensures the assembly sits idle during setup.

Question 35

During RPZ relief valve testing, the relief opens at 2.3 PSID. Is this acceptable?

Accepted Answer

The RPZ relief valve must open at a minimum of 2.0 PSID. A reading of 2.3 PSID exceeds this minimum and indicates proper valve operation and zone protection.

Question 36

Which test cock configuration would indicate pressure directly upstream of Check Valve #1 in a Double Check assembly?

Accepted Answer

Test cock #1, located upstream of the entire assembly, provides the upstream supply pressure. When connected to the high side gauge, it shows the incoming pressure available for testing.

Question 37

After a failed test, what documentation must be prepared?

Accepted Answer

Failed assemblies require a detailed report documenting the test results, which specific component failed, and the recommended action (repair, replacement, or further testing). This protects both the technician and property owner.

Question 38

A technician is testing a Double Check assembly when the gauge on the high side line suddenly drops to zero. What should be done?

Accepted Answer

A sudden pressure drop on the high side indicates a disconnected hose, failed connection, or gauge malfunction. The test must be stopped, the issue corrected, and testing restarted from the beginning.

Question 39

What is the minimum time an RPZ assembly relief valve should sit undisturbed after opening at cracking pressure to ensure it reseats properly?

Accepted Answer

After the relief valve opens during testing, pressure should be held steady to observe when the valve closes and reseating occurs. The technician watches for continuous discharge to stop, indicating proper valve function.

Question 40

In a scenario where an RPZ assembly Check #1 reads 5.1 PSID, relief opens at 1.8 PSID, and Check #2 reads 1.1 PSID, what is the status?

Accepted Answer

The relief valve opens at 1.8 PSID, which is below the 2.0 PSID minimum requirement. Even though Check #1 and #2 pass, the relief valve failure means the assembly cannot protect the zone and must be replaced.

Question 41

When measuring Check Valve #2 in a Double Check assembly, what is being tested?

Accepted Answer

Check Valve #2, the outlet check, prevents water from flowing backward out of the protected zone during a backsiphonage event. It seals the outlet side when pressure drops below system pressure.

Question 42

A Spill-Resistant Vacuum Breaker (SVB) is being tested. What is the primary difference in test procedure from a standard PVB?

Accepted Answer

SVB and PVB assemblies use the same test procedure and PSID requirements (1.0 minimum). The difference is in design (spill-resistant) and installation (indoor vs. outdoor); the testing method is unchanged.

Question 43

What happens if the technician opens the high side needle valve completely and forgets to bleed air before closing the low side to take a reading?

Accepted Answer

Air in the system compresses under pressure and can register falsely high readings. A valve that is actually failing (0.8 PSID) might read 1.1 PSID if air is present, resulting in a false pass.

Question 44

During an RPZ assembly test, after Check #1 testing is complete, what is the next step?

Accepted Answer

After Check #1 passes, the relief valve test is performed. This critical test uses test cocks #2 and #4 (with bypass valve) to verify relief operation at the required 2.0 PSID minimum.

Question 45

A DC assembly test is being performed. After bleeding and closing the low side needle valve for Check #1, the gauge reads 2.4 PSID. What does this indicate?

Accepted Answer

A 2.4 PSID differential well exceeds the 1.0 PSID minimum for DC check valves and indicates excellent seating. Higher differentials are acceptable and indicate strong protection.

Question 46

What is the purpose of the bypass valve connection on an RPZ test kit during relief valve testing?

Accepted Answer

The bypass valve (or needle valve) on test cock #2 during relief testing allows controlled pressure buildup into the zone. The technician watches for relief discharge to identify the cracking pressure.

Question 47

A technician finishes testing a Double Check assembly and begins to open shutoff #2. Water is observed leaking from the relief valve drain port. What does this indicate?

Accepted Answer

A Double Check assembly has no relief valve. Water leaking from a relief drain indicates an unauthorized addition to the assembly or possible misidentification. This requires investigation and corrective action.

Question 48

According to test procedures, what is verified by slowly opening shutoff valve #2 at the end of testing?

Accepted Answer

Slowly opening shutoff #2 during return to service verifies the valve operates smoothly and the assembly functions without leaks when full pressure is restored. Any leaks at seals or connections indicate assembly issues.

Question 49

When the high side gauge is connected to test cock #1 during a preliminary DC test, what pressure is being measured?

Accepted Answer

Test cock #1 is located upstream of the entire assembly and measures the incoming supply pressure. This preliminary reading confirms adequate pressure is available to perform the tests.

Question 50

An RPZ assembly test shows Check #1 at 5.2 PSID, relief at 2.1 PSID, and Check #2 at 0.9 PSID. What is the determination?

Accepted Answer

Check Valve #2 reads 0.9 PSID, which is below the 1.0 PSID minimum for RPZ assemblies. A failing component means the entire assembly cannot protect against backflow and must be replaced.

Question 51

What is the difference between a test that results in a failed component versus one that is inconclusive?

Accepted Answer

A failed test has a clear reading below the minimum requirement. An inconclusive result occurs when gauge malfunction, equipment issues, or procedure errors make the reading unreliable, requiring a retest with confirmed equipment.

Question 52

During DC assembly testing, why must the test cocks be fully seated (closed) when opening shutoff #2 for return to service?

Accepted Answer

Leaving test cocks open during return to service could allow water to leak from the assembly and create an unsafe condition. Closed test cocks ensure the assembly operates in normal service mode.

Question 53

What does it mean if a gauge reading continues to rise even after the low side needle valve is closed and stabilization time is allowed?

Accepted Answer

A rising reading with the low side closed indicates the test fluid is flowing past (through) the check valve, replenishing pressure on the low side. This demonstrates the check valve is not sealing and the assembly is failing.

Question 54

A technician uses a test kit that is 14 months past its calibration date. Can this test be considered valid?

Accepted Answer

Test kits require annual calibration to maintain accuracy within ±0.2 PSID. An expired kit cannot be relied upon for accurate results and invalidates the test. The kit must be recalibrated before testing resumes.

Question 55

What is the primary purpose of the test procedure sequence (preliminary, Check #1, Check #2, and return to service) in the standards?

Accepted Answer

The standardized sequence ensures consistency, eliminates guesswork, and provides documented evidence of assembly performance. Following the exact procedure every time protects the water supply and provides legal documentation.

Test Procedures Practice Questions

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