Master Plumber Exam Backflow Prevention and Safety 4 — Questions and Answers
Question 1: A reduced pressure zone assembly must be installed so that the relief valve outlet is:
- At least 12 inches above the finished floor
- At least 12 inches above the flood level rim of the nearest receptor (Correct answer)
- No more than 5 feet above grade
- Directly connected to a sanitary drain
Correct answer: At least 12 inches above the flood level rim of the nearest receptor
The RPZ relief valve outlet must discharge at least 12 inches above the flood level rim of any receptor or floor to prevent backflow through the discharge port.
Question 2: Which scenario represents backsiphonage rather than backpressure?
- A booster pump increases downstream pressure above supply
- A water main break causes a vacuum in the supply line (Correct answer)
- A closed heating system operates at 90 psi while supply is 80 psi
- A recirculating pump forces water backward through an open check valve
Correct answer: A water main break causes a vacuum in the supply line
Backsiphonage occurs when negative pressure (vacuum) in the supply line siphons contaminants from a downstream source back into the potable supply.
Question 3: What ASSE standard covers pressure vacuum breakers (PVBs) for irrigation applications?
- ASSE 1001
- ASSE 1013
- ASSE 1020 (Correct answer)
- ASSE 1056
Correct answer: ASSE 1020
ASSE 1020 is the standard for pressure vacuum breaker (PVB) assemblies used in irrigation and other plumbing applications.
Question 4: When should a plumber NOT use a pressure vacuum breaker on an irrigation system?
- When the system uses potable water
- When chemicals or fertilizers are injected into the system (Correct answer)
- When the system has a single zone valve
- When ambient temperatures exceed 90°F
Correct answer: When chemicals or fertilizers are injected into the system
Chemical injection (fertilizers, pesticides) creates a health hazard requiring an RPZ assembly — a PVB is insufficient for this level of risk.
Question 5: A backflow preventer installed on a carbonated beverage dispenser connection to the potable water line requires which device?
- Air gap only
- Dual check valve with atmospheric vent (ASSE 1022) (Correct answer)
- RPZ assembly (ASSE 1013)
- Hose connection vacuum breaker (ASSE 1011)
Correct answer: Dual check valve with atmospheric vent (ASSE 1022)
Carbonated beverage dispensers require an ASSE 1022 dual check valve with atmospheric vent because carbonation creates backpressure risk without a health hazard.
Question 6: Which of the following is a requirement for the installation location of a testable backflow assembly such as an RPZ?
- It must be installed underground to protect from freezing
- It must be accessible for testing and maintenance (Correct answer)
- It must be installed before the water meter
- It must be located inside the building only
Correct answer: It must be accessible for testing and maintenance
All testable backflow prevention assemblies must be installed in accessible locations so certified testers can operate test cocks and valves without obstruction.
Question 7: What is the purpose of test cocks on a reduced pressure zone (RPZ) assembly?
- To relieve excess pressure during a water hammer event
- To allow a certified tester to measure differential pressure across each check valve (Correct answer)
- To provide a sampling port for water quality testing
- To allow the assembly to be bypassed during testing
Correct answer: To allow a certified tester to measure differential pressure across each check valve
Test cocks provide connection points for differential pressure gauges so a certified tester can verify each check valve and the relief valve are functioning correctly.
Master Plumber Exam Backflow Prevention and Safety 4
A reduced pressure zone assembly must be installed so that the relief valve outlet is: