Gas Piping Systems Flashcards
7 cards from real Master Plumber 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 Systems flashcards as text
Propane (LP gas) differs from natural gas in a critical safety way because propane:
Answer: Is heavier than air and can accumulate in low areas
Propane has a specific gravity of about 1.5, meaning it is heavier than air and will settle in basements, pits, and low spots creating explosion hazards.
What is the required BTU content used to size natural gas piping when the specific BTU rating of appliances is unknown?
Answer: 1,000 BTU per cubic foot
Natural gas is typically rated at approximately 1,000 BTU per cubic foot for standard piping sizing calculations.
Which type of fitting is NOT approved for use in a gas piping system?
Answer: Cast iron fittings
Cast iron fittings are not approved for gas piping because they are brittle and can crack under pressure or mechanical stress.
When installing a gas meter, what is the minimum required clearance from an electrical meter?
Answer: 3 feet
Gas meters must be installed at least 3 feet away from electrical meters to reduce ignition risk from electrical sparks.
A gas appliance connector (flexible connector) used to connect a range to the gas supply line may be a maximum of:
Answer: 4 feet
Flexible gas appliance connectors are limited to a maximum length of 6 feet to prevent kinking, stress, and concealed installation.
What is the minimum test pressure required for a medium-pressure gas system (above 0.5 psi) under NFPA 54?
Answer: 1.5 times the working pressure, minimum 3 psi
For systems above 0.5 psi, the test pressure must be at least 1.5 times the working pressure with a minimum of 3 psi.
Which valve type is required as the main shutoff at the gas meter on a residential service?
Answer: Ball valve or plug (cock) valve
Ball valves and plug/cock valves are required at meter shutoffs because they provide a positive, quick quarter-turn shutoff and clear open/closed indication.