FREE Master Plumber Drain, Waste, & Vent Systems Questions and Answers

Question 1

A master plumber is installing an island kitchen sink in a location where a conventional vertical vent through the wall is not possible.
Which of the following is a mandatory requirement for an island fixture vent (loop vent) according to most model plumbing codes?

Accepted Answer

The fixture drain upstream of the island vent connection is permitted to serve a garbage disposal and a dishwasher.

Answer

The vent must connect downstream of the trap and rise vertically to the drainboard height before returning down.

Answer

An air admittance valve can be used at the highest point of the loop to simplify the installation.

Answer

The portion of the vent below the floor must be sloped at a minimum of 1/8 inch per foot back to the drain.

Question 2

When performing a water test on a new DWV system constructed of plastic piping, what is the required test pressure and duration specified by the International Plumbing Code?

Accepted Answer

A 10-foot head of water for 15 minutes.

Answer

5 psi of air pressure for 15 minutes.

Answer

A 5-foot head of water for 30 minutes.

Answer

Water-filled to the flood-level rim of the highest fixture for 10 minutes.

Question 3

In a multi-story building, a drainage stack has a horizontal offset. Under which condition is special venting for the offset required according to the IPC?

Accepted Answer

When five or more branch intervals are located above the horizontal offset.

Answer

When any horizontal offset exceeds 5 feet in length.

Answer

When the offset is located one branch interval below the top of the stack.

Answer

When a fixture connects within 10 feet of the offset, either above or below.

Question 4

A plumber is designing a combination waste and vent system for a series of floor drains in a commercial laboratory. Which of the following is a key limitation of this type of system under the IPC?

Accepted Answer

Vertical risers connecting fixture drains to the horizontal pipe cannot exceed 8 feet.

Answer

The maximum developed length of the combination pipe is limited to 50 feet.

Answer

The pipe must be sloped at 1/8 inch per foot to ensure proper scouring action.

Answer

Only a maximum of three fixtures can be connected to any single combination waste and vent pipe.

Question 5

Under the IPC, what is the maximum number of bathroom groups on the same floor level that can be served by a single horizontal wet vent?

Accepted Answer

Two

Answer

One

Answer

Three

Answer

Four

Question 6

A master plumber is installing a sewage ejector pump in a basement sump pit. What is the IPC requirement for venting the sump?

Accepted Answer

The vent size is determined by the pump's discharge rating in gallons per minute (GPM) and the developed length.

Answer

The vent must terminate with an air admittance valve located at least 6 inches above the sump cover.

Answer

The vent must be a minimum of 2 inches in diameter, regardless of the pump's discharge rate.

Answer

The vent must extend independently to the open air and cannot be connected to other vents.