Master Plumber DWV and Storm Drainage Questions and Answers

Question 1

According to most plumbing codes, what is the minimum required air pressure and duration for testing a DWV (Drain, Waste, and Vent) system?

Accepted Answer

5 psi for 15 minutes

Answer

10 psi for 10 minutes

Answer

15 psi for 5 minutes

Answer

5 psi for 30 minutes

Question 2

A plumber is installing a horizontal drainage line for a series of sinks in a commercial building. The total developed length of the 4-inch pipe run is 120 feet. According to common plumbing codes, how many cleanouts are required for this section of piping?

Accepted Answer

One at the beginning, one at the end, and one in the middle

Answer

One at the end of the run

Answer

One at the beginning and one at the end

Answer

One every 50 feet

Question 3

Which of the following is an unacceptable practice when designing or installing a storm drainage system?

Accepted Answer

Connecting the primary roof drain system directly to the sanitary sewer system.

Answer

Sizing conductors and leaders based on the maximum projected roof area and local rainfall rate.

Answer

Discharging storm water onto a flat, graded area away from the building on a residential property.

Answer

Providing a separate, independent secondary (overflow) drain system.

Question 4

In a DWV system, what is the primary purpose of a vent?

Accepted Answer

To equalize air pressure within the drainage system, protecting fixture trap seals from siphonage and back pressure.

Answer

To provide a secondary path for waste in case of a clog.

Answer

To filter out sewer gases before they enter the building.

Answer

To increase the velocity of waste flowing through the pipes.

Question 5

A master plumber is overseeing the installation of an under-floor cleanout in a crawl space with limited access. According to the Uniform Plumbing Code (UPC), what is the maximum distance the cleanout can be from an access door or crawl hole?

Accepted Answer

5 feet

Answer

20 feet

Answer

15 feet

Answer

10 feet

Question 6

When sizing a vertical storm drain conductor for a large commercial building, which of the following factors is most critical?

Accepted Answer

The maximum projected roof area and the local hourly rainfall rate.

Answer

The number of plumbing fixtures in the building.

Answer

The total length of the horizontal storm drain.

Answer

The material of the DWV piping.