Master Plumber Exam Drainage, Waste, and Venting 2

Question 1

What is the minimum slope required for a 3-inch horizontal drain pipe under the IPC?

Accepted Answer

1/8 inch per foot

Answer

The IPC requires a minimum slope of 1/8 inch per foot for 3-inch horizontal drain pipes to ensure proper flow.

Question 2

Which type of vent serves as both a vent for a trap and the drain for a fixture?

Accepted Answer

Wet vent

Answer

A wet vent simultaneously carries waste water from one fixture and provides the vent for another fixture's trap.

Question 3

Under the IPC, what is the maximum distance a P-trap for a lavatory can be from its vent?

Accepted Answer

4 feet

Answer

The IPC allows a maximum developed length of 4 feet between a lavatory trap and its vent connection.

Question 4

A building drain that transitions to a building sewer must maintain the same slope unless:

Accepted Answer

The sewer pipe is larger in diameter

Answer

When the building sewer pipe is larger than the building drain, a change in slope is permissible at the transition point.

Question 5

Which fitting is prohibited for use in a horizontal-to-vertical drain change of direction?

Accepted Answer

Sanitary tee used on its side

Answer

A sanitary tee used on its side (horizontal flow) is prohibited because its design creates turbulence and restricts drainage flow.

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