Master Plumber Exam Backflow Prevention and Safety 2

Question 1

Which backflow preventer is required when the downstream system contains a non-health hazard pollutant but not a contaminant?

Accepted Answer

Double check valve assembly (DCVA)

Answer

A double check valve assembly is the minimum required protection for low-hazard (pollutant) cross-connections where health risk is not present.

Question 2

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?

Accepted Answer

2 times the diameter of the supply pipe or 1 inch, whichever is greater

Answer

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.

Question 3

A pressure vacuum breaker (PVB) differs from an atmospheric vacuum breaker (AVB) primarily because the PVB:

Accepted Answer

Contains a spring-loaded check valve and can remain under continuous pressure

Answer

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.

Question 4

When testing a reduced pressure zone (RPZ) assembly, which condition indicates the device has passed?

Accepted Answer

The second check holds at least 1 psi with no differential reading

Answer

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.

Question 5

Which type of cross-connection is created when a garden hose is left submerged in a swimming pool connected to the potable water system?

Accepted Answer

Direct cross-connection

Answer

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.

Master Plumber Exam Practice Test

Master Plumber Exam Practice Test

Master Plumber Exam Backflow Prevention and Safety 2