Plumbing Drainage, Waste & Vent (DWV)

Question 1

What is the primary purpose of a vent pipe in a plumbing system?

Accepted Answer

To maintain air pressure and prevent siphoning of trap seals

Answer

Vent pipes maintain atmospheric pressure in the drain system, preventing the siphoning of water from trap seals that would allow sewer gases to enter the building.

Question 2

What is the minimum water seal depth required in a standard P-trap?

Accepted Answer

2 inches

Answer

The IPC requires a minimum water seal depth of 2 inches in a P-trap to prevent sewer gases from entering the building.

Question 3

What type of trap is prohibited in most US plumbing codes?

Accepted Answer

S-trap

Answer

S-traps are prohibited because they are prone to self-siphonage, which can empty the water seal and allow sewer gases into the building.

Question 4

What does 'wet venting' mean in a plumbing system?

Accepted Answer

A single pipe that serves as both a drain and a vent

Answer

Wet venting uses a single oversized pipe that serves simultaneously as a drain for one fixture and a vent for another downstream fixture.

Question 5

What is the term for a fitting that connects a branch drain to a vertical stack?

Accepted Answer

Sanitary tee

Answer

A sanitary tee is used to connect branch drain lines to a vertical stack, with its swept inlet directing flow downward to prevent turbulence.

Plumbing Practice Test

Plumbing Practice Test

Plumbing Drainage, Waste & Vent (DWV)