Backflow Prevention and Safety Flashcards
7 cards from real Master Plumber Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Backflow Prevention and Safety flashcards as text
Which backflow preventer is required when the downstream system contains a non-health hazard pollutant but not a contaminant?
Answer: Double check valve assembly (DCVA)
A double check valve assembly is the minimum required protection for low-hazard (pollutant) cross-connections where health risk is not present.
What is the minimum air gap distance required between a potable water supply outlet and the flood level rim of a fixture under most US plumbing codes?
Answer: 2 times the diameter of the supply pipe or 1 inch, whichever is greater
The air gap must be at least twice the diameter of the supply pipe or 1 inch, whichever is greater, to prevent backflow by siphonage.
A pressure vacuum breaker (PVB) differs from an atmospheric vacuum breaker (AVB) primarily because the PVB:
Answer: Contains a spring-loaded check valve and can remain under continuous pressure
The PVB has an internally loaded check valve that allows it to remain under continuous supply pressure, unlike the AVB which must not be under continuous pressure.
When testing a reduced pressure zone (RPZ) assembly, which condition indicates the device has passed?
Answer: The second check holds at least 1 psi with no differential reading
A passing RPZ test requires the second check to hold tight (no differential relief) and proper differential pressure readings across both checks and the relief valve.
Which type of cross-connection is created when a garden hose is left submerged in a swimming pool connected to the potable water system?
Answer: Direct cross-connection
A direct cross-connection is a physical link between a potable supply line and a non-potable source, such as a hose submerged in a pool.
Under the Uniform Plumbing Code (UPC), backflow preventers installed on irrigation systems serving areas that use pesticides or fertilizers must be at minimum:
Answer: Reduced pressure zone (RPZ) assembly
Chemicals such as pesticides and fertilizers represent a high-hazard (health risk) condition, requiring an RPZ assembly as the minimum protection.
What is backpressure backflow?
Answer: Backflow caused by downstream pressure exceeding supply pressure
Backpressure backflow occurs when the downstream pressure rises above the supply pressure, forcing contaminants upstream into the potable system.