Gas Piping and Appliances 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 Appliances flashcards as text
What is the minimum clearance required between an unprotected gas appliance vent connector and combustible material?
Answer: 6 inches
NFPA 54 requires a minimum 6-inch clearance between an unprotected single-wall metal vent connector and combustible materials.
Which pipe material is NOT approved for use with natural gas in residential installations under NFPA 54?
Answer: PVC plastic pipe
PVC plastic pipe is not permitted for gas piping because it cannot withstand the temperatures and pressures involved and is not listed for gas service.
A gas appliance draft hood is designed primarily to:
Answer: Prevent backdrafting from affecting burner operation
A draft hood (or draft diverter) protects the appliance burner from downdrafts and pressure fluctuations in the venting system.
When sizing a gas piping system, the pressure drop allowed in a low-pressure system (under 2 psi) from the meter to the appliance is typically:
Answer: 0.5 inch WC
For low-pressure systems, NFPA 54 sizing tables are based on a 0.5 inch WC pressure drop from the meter to the most remote appliance.
A gas dryer vent must terminate:
Answer: At least 3 feet from any opening into the building
Dryer exhaust vents must terminate outdoors at least 3 feet from any building opening such as windows, doors, or vents to prevent re-entry of combustion products.
What type of fitting is prohibited in a concealed gas piping installation?
Answer: Compression fittings
Compression fittings are not listed for gas service and are prohibited in concealed gas piping installations where leaks cannot be easily detected.
The purpose of a sediment trap (drip leg) installed at a gas appliance is to:
Answer: Catch moisture and debris before they reach the appliance valve
A sediment trap collects condensate and pipe scale that would otherwise clog or damage the appliance's gas valve and controls.