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

A Reduced Pressure Zone (RPZ) assembly provides the highest level of protection and is required for high-hazard applications where contaminants like cleaning chemicals could cause illness or death if they enter the potable water system. A DCVA is for low-hazard situations, while AVBs and PVBs only protect against back-siphonage, not back-pressure.

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-siphonage is the reversal of flow caused by a reduction in system pressure, which creates a partial vacuum that can pull contaminants into the potable water supply. This is different from back-pressure, which occurs when downstream pressure is higher than the supply pressure.

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

An air gap is a physical separation between the free-flowing discharge end of a potable water supply pipe and the flood-level rim of a receptacle. It is the most reliable and simplest method of backflow prevention because there is no physical connection for contaminants to cross.

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

An AVB must be installed vertically and at least 6 inches (or as specified by code) above the highest point of use to allow air to enter and break a vacuum. It cannot have any shut-offs downstream and is not designed for continuous pressure or to protect against 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 cross-connection is any actual or potential link between a potable water system and a source of contamination. Submerging a hose connected to the potable supply into a non-potable solution like pesticides creates a direct cross-connection. If a back-siphonage event occurs, the pesticide will be drawn into the water supply. The other options describe properly protected connections.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Backflow Prevention Questions and Answers