Master Plumber Plumbing System Design Questions and Answers

Question 1

A master plumber is designing a storm drainage system for a commercial building with a 12,000 square foot roof area.
The local code specifies a 100-year hourly rainfall rate of 4 inches/hour.
What is the minimum required diameter for a horizontal storm drain with a 1/4-inch-per-foot (2%) slope?

Accepted Answer

6 inches

Answer

4 inches

Answer

5 inches

Answer

8 inches

Question 2

A commercial kitchen is being fitted with a three-compartment sink. Each compartment measures 24 inches long, 24 inches wide, and has a water depth of 12 inches. Using the fixture volume method with a 75% loading factor and a one-minute drainage period, what is the minimum required GPM flow rate for the hydromechanical grease interceptor?

Accepted Answer

67 GPM

Answer

30 GPM

Answer

90 GPM

Answer

45 GPM

Question 3

Which of the following is a mandatory requirement for a circuit vent installation under the International Plumbing Code?

Accepted Answer

The vent connection to the horizontal branch must be located between the two most upstream fixture drains.

Answer

The vent must be a minimum of 2 inches in diameter, regardless of the drain size.

Answer

The circuit vent can serve a maximum of six fixtures on a single horizontal branch.

Answer

The horizontal branch being circuit vented must have a minimum slope of 1/2 inch per foot.

Question 4

A master plumber is designing a subsoil drainage system for a new building that terminates in an interior sump pit with an automatic pump. According to model plumbing codes, where must the discharge from the sump pump be terminated?

Accepted Answer

To the building storm drain, a dry well, or an approved point of discharge outside the building.

Answer

Directly into the building's sanitary drainage system below the basement floor.

Answer

Into a laundry utility sink through an approved air gap fitting.

Answer

Into the vent stack for the sanitary system to ensure it is properly diluted.

Question 5

According to NFPA 99, medical gas piping must be clearly labeled for safety and identification. Which of the following is a correct labeling requirement?

Accepted Answer

Applying labels indicating the gas name and direction of flow at intervals not exceeding 20 feet.

Answer

Painting the entire length of the pipe with the gas-specific color code.

Answer

Using stamped metal tags at every valve and wall penetration only.

Answer

Labeling is only required in patient care areas and mechanical rooms.

Question 6

In which of the following scenarios is the installation of a trap primer most critical to prevent the release of sewer gas?

Accepted Answer

A floor drain located in a seldom-used mechanical room.

Answer

A kitchen sink in a busy restaurant.

Answer

A lavatory P-trap in a high-traffic public restroom.

Answer

A bathtub drain in a frequently occupied hotel suite.

A master plumber is designing a storm drainage system for a commercial building with a 12,000 square foot roof area.The local code specifies a 100-year hourly rainfall rate of 4 inches/hour.What is the minimum required diameter for a horizontal storm drain with a 1/4-inch-per-foot (2%) slope?

A master plumber is designing a storm drainage system for a commercial building with a 12,000 square foot roof area.
The local code specifies a 100-year hourly rainfall rate of 4 inches/hour.
What is the minimum required diameter for a horizontal storm drain with a 1/4-inch-per-foot (2%) slope?