Master Plumber Exam Plumbing System Design 3

Question 1

Which type of water heater installation requires a dedicated sealed combustion air supply from outside the building?

Accepted Answer

Direct vent (Category IV) gas water heaters

Answer

Direct vent Category IV appliances draw combustion air from outdoors through a sealed concentric pipe system, eliminating indoor air dependency.

Question 2

When sizing a grease interceptor for a commercial kitchen, the design capacity is primarily based on which factor?

Accepted Answer

The flow rate of fixtures served and a retention time factor

Answer

Grease interceptor sizing uses the total fixture flow rate (GPM) multiplied by a retention time, per PDI G101 or local code.

Question 3

In a storm drainage system design, the 100-year storm event rainfall intensity is used to calculate which parameter?

Accepted Answer

The required pipe diameter and roof drain capacity

Answer

Roof drain and storm pipe sizing is calculated using the design rainfall intensity (inches/hour) for the local 100-year storm to ensure adequate capacity.

Question 4

A dual-check backflow preventer is the minimum required protection for which type of cross-connection?

Accepted Answer

Residential water softeners and humidifiers

Answer

Dual-check assemblies are acceptable for low-hazard applications like residential water softeners and humidifiers that present no health hazard.

Question 5

The developed length of a gas supply pipe is used in conjunction with which other value to determine minimum pipe diameter from code tables?

Accepted Answer

Operating pressure and total BTU demand

Answer

Gas pipe sizing tables require both the developed length of piping and the total BTU/hr demand of all connected appliances at the design operating pressure.

Master Plumber Exam Practice Test

Master Plumber Exam Practice Test

Master Plumber Exam Plumbing System Design 3