Venting and Backflow Prevention Flashcards
7 cards from real Journeyman Plumbers 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 Venting and Backflow Prevention flashcards as text
When a common vent connects two fixture drains at the same level, each drain must enter the vertical stack at:
Answer: The same fitting with a double-wye
A common vent requires a double-wye or similar approved fitting that allows both fixture drains to enter at the same elevation.
What is the minimum slope for a horizontal wet vent pipe?
Answer: 1/4 inch per foot
Horizontal wet vent pipes must slope at least 1/4 inch per foot toward the drain to maintain proper flow and self-scouring velocity.
An atmospheric vacuum breaker installed on an irrigation system must be located at least how far above the highest downstream outlet?
Answer: 6 inches
Atmospheric vacuum breakers must be installed at least 6 inches above the highest downstream outlet to prevent submersion and backflow.
Which situation requires a backflow preventer on a potable water supply to a boiler?
Answer: When chemical treatment is added to the boiler water
Chemical additives in boiler water create a high-hazard cross-connection, requiring at minimum an RPZ assembly to protect the potable supply.
A relief vent is used to:
Answer: Restore air circulation in a system where excessive positive pressure occurs
A relief vent is installed to restore air circulation and relieve positive or negative pressure at a critical point in the drainage system.
What is the minimum size vent stack required for a building drain carrying 100 drainage fixture units (DFU)?
Answer: 4 inches
Per IPC venting tables, a vent stack serving a building drain with 100 DFUs requires a minimum 4-inch vent stack.
Where must a relief vent connect to the vent stack when installed at a branch interval?
Answer: Between the branch drain and the next higher branch
A relief vent at a branch interval must connect to the vent stack at a point between the branch drain it serves and the next higher branch drain connection.