Gas Piping Systems Flashcards

When sizing a natural gas pipe, which of the following factors is NOT used in the calculation?

Answer: Color of the pipe material

Gas pipe sizing is based on BTU demand, pipe length, and allowable pressure drop — pipe color has no engineering significance in sizing calculations.

What unit is commonly used to measure low natural gas operating pressure in residential systems?

Answer: Inches of water column (in. WC)

Inches of water column (in. WC) is the standard unit for low residential gas pressures, where 27.7 in. WC equals 1 psi.

Which type of fitting is NOT permitted for concealed gas piping inside a building?

Answer: Compression fitting

Compression fittings are not approved for concealed gas piping because they are mechanical connections that can loosen over time and are not reliably gas-tight.

What material is PROHIBITED for use as interior gas piping inside a residential building?

Answer: PVC or CPVC plastic pipe

PVC and CPVC plastic pipes are not approved for interior gas service because they cannot withstand gas permeation, heat, and physical damage requirements.

Where must a manual gas shutoff valve be installed for a new gas appliance?

Answer: Within 6 feet of the appliance in the same room, in an accessible location

Code requires an accessible manual shutoff valve within 6 feet of each gas appliance in the same room so it can be quickly reached in an emergency.

What is the maximum typical low-pressure natural gas system operating pressure for residential appliances?

Answer: 0.5 psi (14 in. WC)

Residential natural gas appliances typically operate at low pressure — commonly 7 in. WC for most appliances, with a maximum of about 14 in. WC (0.5 psi) at the appliance.

What is the minimum required separation between a gas meter and electrical service equipment?

Answer: 3 feet

Most codes require at least 3 feet of clearance between a gas meter and electrical service equipment to reduce the risk of a spark igniting a gas leak.