Master Plumber Exam DWV and Storm Drainage 3

Question 1

What is the purpose of a cleanout in a DWV system?

Accepted Answer

To provide access for clearing stoppages

Answer

Cleanouts provide access points into drain piping so stoppages can be cleared without dismantling the pipe system.

Question 2

Under the IPC, what is the maximum horizontal distance from a trap to its vent for a 1.5-inch trap arm?

Accepted Answer

5 feet

Answer

Per IPC Table 909.1, a 1.5-inch trap arm may not exceed 5 feet from the trap to the vent connection.

Question 3

A relief vent is installed primarily to prevent which condition?

Accepted Answer

Pressure buildup in the stack that could unseal traps on lower floors

Answer

A relief vent connects the waste stack to the vent stack to relieve positive pressure that can form at the base of tall stacks and blow trap seals.

Question 4

What is the minimum size of a building sewer serving a single-family residence?

Accepted Answer

4 inches

Answer

The IPC requires a minimum 4-inch building sewer for a single-family dwelling because it serves a water closet.

Question 5

A 'wet vent' serves what dual function?

Accepted Answer

It simultaneously acts as a drain for one fixture and a vent for others

Answer

A wet vent carries the discharge of one fixture while also providing the vent path for other fixtures connected upstream.

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