Plumber Water & Drainage Flashcards

What is the fixture unit value assigned to a standard toilet (water closet) for drainage load calculations?

Answer: 4 DFUs

A standard gravity-flush toilet is assigned 4 drainage fixture units (DFUs) under the IPC for sizing drain pipes.

A backwater valve (backflow preventer) installed on a building drain protects against which condition?

Answer: Sewage backing up from the municipal sewer into the building

A backwater valve prevents municipal sewer sewage from flowing backward into the building during a sewer overflow event.

What is the maximum allowable working pressure for standard Schedule 40 PVC pressure pipe at 73°F?

Answer: 160 psi

Schedule 40 PVC pipe is rated at approximately 160 psi working pressure at 73°F for a 1-inch diameter pipe (varies slightly by size).

When solvent cementing PVC pipe, what must be applied to both the pipe and fitting before the solvent cement?

Answer: Purple primer

Purple primer (PVC primer) must be applied to both the pipe end and fitting socket before solvent cement to clean and soften the PVC for a proper bond.

A grease trap is required when installing commercial kitchen drainage. Where is it installed?

Answer: Between the kitchen fixtures and the sanitary drain system

A grease trap is installed between commercial kitchen fixtures and the sanitary drain to intercept fats, oils, and grease before they enter the sewer.

What is a 'critical level' (C-L) marking on a backflow preventer?

Answer: The flood level line of the device, indicating minimum installation height above the flood rim

The C-L mark shows the flood level of the backflow preventer and must be installed at or above the flood level rim of the fixture it serves.

Which venting method uses a single vent pipe to serve multiple fixtures on the same floor level connected to a common horizontal drain?

Answer: Circuit venting

Circuit venting uses one vent pipe at the downstream end of a horizontal branch to serve multiple fixtures connected to that branch.