Journeyman Plumbers Exam Venting and Backflow Prevention 4

Question 1

When a common vent connects two fixture drains at the same level, each drain must enter the vertical stack at:

Accepted Answer

The same fitting with a double-wye

Answer

A common vent requires a double-wye or similar approved fitting that allows both fixture drains to enter at the same elevation.

Question 2

What is the minimum slope for a horizontal wet vent pipe?

Accepted Answer

1/4 inch per foot

Answer

Horizontal wet vent pipes must slope at least 1/4 inch per foot toward the drain to maintain proper flow and self-scouring velocity.

Question 3

An atmospheric vacuum breaker installed on an irrigation system must be located at least how far above the highest downstream outlet?

Accepted Answer

6 inches

Answer

Atmospheric vacuum breakers must be installed at least 6 inches above the highest downstream outlet to prevent submersion and backflow.

Question 4

Which situation requires a backflow preventer on a potable water supply to a boiler?

Accepted Answer

When chemical treatment is added to the boiler water

Answer

Chemical additives in boiler water create a high-hazard cross-connection, requiring at minimum an RPZ assembly to protect the potable supply.

Question 5

A relief vent is used to:

Accepted Answer

Restore air circulation in a system where excessive positive pressure occurs

Answer

A relief vent is installed to restore air circulation and relieve positive or negative pressure at a critical point in the drainage system.

Journeyman Plumbers Exam Practice Test