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
What is the minimum diameter for a vent pipe serving a 3-inch drain pipe under the IPC?
Answer: 1.5 inches
The vent pipe must be at least half the diameter of the drain it serves, with a minimum of 1.25 inches, making 1.5 inches the standard minimum for a 3-inch drain.
A circuit vent is connected to a horizontal branch drain at what location relative to the fixture connections?
Answer: Downstream of the last fixture
A circuit vent connects to the horizontal branch drain downstream (below) the last fixture connection on that branch.
What type of backflow preventer is required on a hose bibb supplying potable water?
Answer: Vacuum breaker
A hose-connection vacuum breaker (HCVB) is required on hose bibbs to prevent siphonage of potentially contaminated water back into the supply.
Under which condition is a wet vent system NOT permitted?
Answer: When the drain serves more than one floor
Wet venting is generally limited to a single story; drains serving fixtures on multiple floors require conventional venting.
Which device provides the highest level of backflow protection and is required for high-hazard connections?
Answer: Reduced pressure zone (RPZ) assembly
The reduced pressure zone assembly is the highest-rated mechanical backflow preventer and is required for high-hazard cross-connections such as chemical feed lines.
How far must a vent pipe terminal extend above a roof that is used for purposes other than weather protection?
Answer: 7 feet
When a roof is used as a deck, garden, or other occupied space, vent terminals must extend at least 7 feet above the roof surface to protect occupants from sewer gases.
What is the purpose of a running trap installed on a building drain?
Answer: To prevent backflow of sewer gases into the building
A running trap (house trap) provides a water seal between the building drain and the public sewer to block sewer gases from entering the building.