Core plumbing code concepts, pipe materials, and fixture installation rules tested on entry-level plumbing licensing exams.
39 cards · basic cards · AI-written, checked twice. Edit anything.
- What is a P-trap and why is it required?
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A P-shaped bend in drainage piping that holds standing water to seal the drain, preventing sewer gases from entering the building.- Why is an S-trap prohibited by most plumbing codes?
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An S-trap can lose its water seal through siphoning, allowing sewer gases to enter the building.- What is the standard trap seal depth?
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Two inches of standing water in the trap.- What is the minimum pitch required for drainage pipes?
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One quarter inch per foot of pipe length (1/4" per foot).- What is the standard rough-in height for a wall-mounted toilet flange?
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Twelve inches from the finished floor to the centerline of the flange.- What is the standard rough-in height for a bathroom lavatory (sink)?
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Thirty-one inches from the finished floor to the centerline of the drain.- What is the minimum diameter of a main vent stack?
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Two inches, unless local code specifies otherwise.- Why must an island sink have a secondary vent?
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An island sink cannot be vented through the roof in the normal way because it has no wall to house the vent, so it requires a separate vent line under the floor.- What size vent is required for most kitchen sinks?
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One and one half inches (1.5"), though 1.25" is allowed in some codes.- What is the maximum distance a trap arm can extend before requiring a vent?
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Six feet from the trap outlet to the vent opening, though some codes allow up to 8 feet for certain fixtures.- What is a wet vent?
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A vent pipe that also carries wastewater from another fixture, allowing multiple fixtures to share a single vent line.- What is a dry vent?
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A vent pipe that carries only air and no wastewater, used solely for venting sewer gases.- What is the maximum water supply pressure allowed in residential plumbing?
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Eighty pounds per square inch (psi); pressures above this require a pressure regulator.- What is the minimum water pressure for residential fixtures?
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Twenty pounds per square inch (psi).- What is backflow prevention?
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A system or device that prevents contaminated or non-potable water from flowing backwards into the public water supply.
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