ABC Backflow Prevention Assembly 3 — Questions and Answers
Question 1: A reduced pressure principle assembly must be installed with a minimum clearance above grade or the floor to allow for:
- Easier access to the shut-off valves only
- Observation, testing, and drainage of the relief valve discharge (Correct answer)
- Protection from freezing temperatures
- Compliance with fire code requirements
Correct answer: Observation, testing, and drainage of the relief valve discharge
Minimum clearance is required so the relief valve can discharge freely and testers can observe, service, and test the assembly without obstruction.
Question 2: Which test cock on a double check valve assembly is used to introduce test equipment pressure to the space between the two check valves?
- Test cock #1
- Test cock #2
- Test cock #3 (Correct answer)
- Test cock #4
Correct answer: Test cock #3
Test cock #3 is located between the two check valves on a DCVA and is used to introduce or bleed pressure in the interspace during differential pressure testing.
Question 3: What is the minimum upstream supply pressure typically required for a pressure vacuum breaker to operate correctly?
- 1 psi
- 5 psi (Correct answer)
- 15 psi
- 25 psi
Correct answer: 5 psi
A PVB requires a minimum of 5 psi supply pressure above the critical level (highest downstream outlet) to maintain the check valve in the closed position.
Question 4: Why is a pressure vacuum breaker (PVB) NOT acceptable for use against back-pressure conditions?
- It is only approved for low-hazard applications
- Back-pressure can force the check valve open, defeating protection (Correct answer)
- PVBs are too expensive for back-pressure applications
- PVBs require more maintenance than RP assemblies
Correct answer: Back-pressure can force the check valve open, defeating protection
A PVB is designed only for backsiphonage protection; back-pressure from downstream can overcome the check valve spring and force the check open, allowing backflow.
Question 5: Which of the following installation conditions would DISQUALIFY a pressure vacuum breaker?
- Installed on an irrigation system
- Installed indoors in a heated mechanical room
- Installed below the highest downstream outlet (Correct answer)
- Installed with a listed shutoff valve upstream
Correct answer: Installed below the highest downstream outlet
A PVB must be installed at least 12 inches ABOVE the highest downstream outlet; installation below the highest outlet allows back-pressure to develop, defeating the device.
Question 6: During an RP assembly test, the relief valve is observed dripping slowly. The tester should first:
- Replace the assembly immediately
- Record the assembly as passing and note the drip
- Test the #1 check valve differential to determine if the relief is responding to a failing check (Correct answer)
- Increase upstream supply pressure to stop the drip
Correct answer: Test the #1 check valve differential to determine if the relief is responding to a failing check
A dripping relief valve typically indicates the #1 check valve differential has dropped below the relief valve opening point; testing the #1 check first identifies the root cause.
Question 7: The ABC certification exam for backflow prevention testers is administered under which national standard?
- AWWA M14
- ASSE 5000 (Correct answer)
- USC FCCCHR List of Approved Backflow Prevention Assemblies
- USC FCCCHR Standard: Tester Certification Requirements
Correct answer: ASSE 5000
The ABC uses ASSE 5000 as the professional qualification standard for backflow prevention assembly testers, covering knowledge and field testing competencies.
ABC Backflow Prevention Assembly 3
A reduced pressure principle assembly must be installed with a minimum clearance above grade or the floor to allow for: