Journeyman Plumbers Exam Gas Piping and Venting 2

Question 1

What is the minimum clearance required between a gas appliance vent connector and combustible materials?

Accepted Answer

6 inches

Answer

NFPA 54 requires a minimum 6-inch clearance between single-wall metal vent connectors and combustible materials.

Question 2

When sizing a gas piping system, what is the primary factor used to determine pipe diameter?

Accepted Answer

BTU demand and pipe length combined

Answer

Gas pipe sizing requires both the total BTU demand of all appliances and the total developed length of the longest run to be considered.

Question 3

Which type of gas valve is required to be installed immediately upstream of each gas appliance?

Accepted Answer

Accessible manual shutoff valve

Answer

An accessible manual shutoff valve must be installed within 6 feet of each appliance to allow quick isolation in an emergency.

Question 4

A Type B gas vent must terminate at least how far above the roof surface when the roof slope is 6/12 or less?

Accepted Answer

2 feet

Answer

For roof slopes of 6/12 or less, Type B vents must extend at least 2 feet above the highest point where the vent passes through the roof.

Question 5

What is the maximum allowable pressure drop for a low-pressure residential gas distribution system serving appliances?

Accepted Answer

0.5 inch W.C.

Answer

Low-pressure residential systems must not lose more than 0.5 inch W.C. between the meter outlet and any appliance connection.

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