Gas Piping and Venting Flashcards
7 cards from real Journeyman Plumbers Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Gas Piping and Venting flashcards as text
What is the minimum clearance required between a gas appliance vent connector and combustible materials?
Answer: 6 inches
NFPA 54 requires a minimum 6-inch clearance between single-wall metal vent connectors and combustible materials.
When sizing a gas piping system, what is the primary factor used to determine pipe diameter?
Answer: BTU demand and pipe length combined
Gas pipe sizing requires both the total BTU demand of all appliances and the total developed length of the longest run to be considered.
Which type of gas valve is required to be installed immediately upstream of each gas appliance?
Answer: Accessible manual shutoff valve
An accessible manual shutoff valve must be installed within 6 feet of each appliance to allow quick isolation in an emergency.
A Type B gas vent must terminate at least how far above the roof surface when the roof slope is 6/12 or less?
Answer: 2 feet
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.
What is the maximum allowable pressure drop for a low-pressure residential gas distribution system serving appliances?
Answer: 0.5 inch W.C.
Low-pressure residential systems must not lose more than 0.5 inch W.C. between the meter outlet and any appliance connection.
Which material is NOT approved for use in gas piping inside a residential building?
Answer: PVC plastic pipe
PVC plastic pipe is not approved for interior gas piping because it is not rated for gas service in most jurisdictions.
When a gas vent connector passes through a combustible interior wall, what must be installed?
Answer: An approved thimble or listed wall pass-through
An approved thimble or listed wall pass-through fitting must be used to maintain required clearances when a vent connector penetrates a combustible wall.