TheoryBackflow Tester Practice Questions
Free Backflow Tester practice questions with answers and plain-English explanations. Browse the PDF, video and online mock test.
Backflow Tester Questions
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Q1Which component in a Reduced Pressure Zone (RPZ) assembly maintains a differential pressure zone between the two check valves?
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✓ Correct answer: Relief valve
The relief valve in an RPZ assembly vents to atmosphere whenever the differential pressure between the two check valves drops below 2 psi, maintaining a reduced pressure zone. This is the defining characteristic of the RPZ assembly.
Q2How many independently acting check valves does a standard Reduced Pressure Zone (RPZ) assembly contain?
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✓ Correct answer: Two
An RPZ assembly contains two independently acting, spring-loaded check valves in series. The space between them is the reduced pressure zone monitored by the relief valve.
Q3What type of shutoff valves are typically required on either side of a testable backflow preventer assembly?
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✓ Correct answer: Full-port ball valves or resilient-seated gate valves
Full-port ball valves or resilient-seated gate valves are required as shutoff valves flanking testable backflow preventers because they allow full, unobstructed flow and can be fully closed for isolation and testing.
Q4A Double Check Valve Assembly (DCVA) consists of two check valves, two shutoff valves, and which additional feature that distinguishes it from a simple dual-check?
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✓ Correct answer: Test cocks between and outside the checks
A DCVA includes test cocks (typically four) that allow field testing of each check valve independently, unlike a simple dual-check that has no test ports. This testability is required for cross-connection control programs.
Q5A Pressure Vacuum Breaker (PVB) assembly must be installed at what minimum height above the highest downstream outlet or usage point?
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✓ Correct answer: 6 inches
A PVB must be installed at least 6 inches above the highest downstream outlet or point of use to prevent the downstream system from submerging the air inlet valve, which could allow back-siphonage contamination.
Q6Which of the following hazard types can a Pressure Vacuum Breaker (PVB) protect against?
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✓ Correct answer: Back-siphonage only
A PVB protects only against back-siphonage. Because it opens to atmosphere under negative pressure, it cannot seal against backpressure conditions; for backpressure hazards an RPZ or DCVA must be used.
Q7An Atmospheric Vacuum Breaker (AVB) must NOT be installed where it may be subjected to continuous pressure for more than how many hours?
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✓ Correct answer: 12 hours
An AVB is rated for intermittent service only and must not remain under continuous supply pressure for more than 12 hours, because the float/poppet seal can deform and fail, losing backflow protection.
Q8Where must an Atmospheric Vacuum Breaker (AVB) be located relative to any downstream shutoff valve?
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✓ Correct answer: Upstream of all downstream shutoff valves
An AVB must be upstream of all downstream shutoff valves. If a shutoff valve is downstream of the AVB and is closed, pressure can be trapped and held against the AVB, defeating its operation.
Q9During an RPZ field test, the differential pressure across the first check valve (check #1) must be at least how many psid to pass?
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✓ Correct answer: 1.0 psid
The first check valve of an RPZ must maintain a differential pressure of at least 1.0 psid when tested. The relief valve must open at 2.0 psid below the supply pressure, but the check itself is evaluated at the 1.0 psid threshold.
Q10When testing an RPZ assembly, the relief valve must open at a differential pressure no less than:
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✓ Correct answer: 2.0 psid below the supply pressure
The RPZ relief valve must open when the differential pressure between the zone and supply falls to at least 2.0 psid. If it opens at less than 2.0 psid the zone may not be adequately protected; if it never opens the device fails.
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