Journeyman Plumbers Backflow Prevention Questions and Answers

Question 1

A commercial kitchen is installing a new chemical dispensing unit that connects directly to the potable water supply to mix cleaning solutions.
This is considered a high-hazard application.
Which of the following backflow prevention devices is required for this installation?

Accepted Answer

Reduced Pressure Zone Assembly (RPZ)

Answer

Double Check Valve Assembly (DCVA)

Answer

Atmospheric Vacuum Breaker (AVB)

Answer

Pressure Vacuum Breaker (PVB)

Question 2

What type of backflow is caused by a negative or sub-atmospheric pressure in the water supply piping, often resulting from a water main break or firefighting activities nearby?

Accepted Answer

Back-siphonage

Answer

Back-pressure

Answer

Hydraulic shock

Answer

Cross-contamination

Question 3

Which of the following backflow prevention devices is considered the most effective and simplest form, providing a physical separation between the potable water outlet and a potential contaminant?

Accepted Answer

Air Gap

Answer

Double Check Valve Assembly (DCVA)

Answer

Reduced Pressure Zone Assembly (RPZ)

Answer

Pressure Vacuum Breaker (PVB)

Question 4

An Atmospheric Vacuum Breaker (AVB) is a common backflow prevention device. What is a key installation requirement and operational limitation of an AVB?

Accepted Answer

It must be installed at least 6 inches above all downstream piping and outlets.

Answer

It can be installed below the flood level rim of the fixture it serves.

Answer

It is suitable for applications with continuous line pressure.

Answer

It is designed to protect against both back-siphonage and back-pressure.

Question 5

Which of the following scenarios describes an unprotected cross-connection that could lead to a dangerous backflow event?

Accepted Answer

A garden hose with its end submerged in a bucket of pesticide solution.

Answer

A faucet spout terminating 2 inches above the flood level rim of a lavatory.

Answer

A commercial boiler connected to the potable water supply via an RPZ assembly.

Answer

A toilet fill valve with an integral anti-siphon device installed above the critical level.

Question 6

A plumber notices that the relief valve on a newly installed Reduced Pressure Zone (RPZ) assembly is constantly discharging a small amount of water. What is the most likely cause?

Accepted Answer

The number 2 check valve is fouled or leaking.

Answer

The device is functioning perfectly as designed.

Answer

The inlet water pressure is too low.

Answer

The outlet shutoff valve is partially closed.