G3 - Gas Technician Level 3 Pressure Regulation and Control Questions and Answers Flashcards

An overpressure protection device (OPD) on a gas regulator is designed to:

Answer: Shut off or limit gas flow if downstream pressure exceeds a safe level

OPDs protect downstream piping and appliances by closing or relieving gas flow when outlet pressure rises above a set threshold.

When checking gas pressure with a manometer, the technician connects the instrument to:

Answer: A pressure test port or tap on the appliance manifold or supply piping

Gas pressure is measured at dedicated test ports on the supply manifold or piping, ensuring an accurate and safe reading.

For LP (propane) gas appliances in the US, the typical operating manifold pressure is:

Answer: 11 in. W.C.

LP (propane) appliances in the US are designed to operate at 11 in. W.C. manifold pressure, compared to 3.5 in. W.C. for natural gas.

A two-stage LP regulator system uses a first-stage regulator to reduce tank pressure to approximately:

Answer: 10 psi

In a two-stage LP system, the first-stage regulator reduces high tank pressure (up to 200 psi) to approximately 10 psi intermediate pressure.

If a gas appliance has a weak or lazy flame and the manifold pressure is found to be lower than specified, the technician should check:

Answer: The supply pressure at the regulator outlet and the regulator set-point adjustment

Low manifold pressure typically traces back to an incorrectly set or failing regulator, low line pressure, or a partially closed supply valve.

A regulator that allows full supply pressure to pass to downstream piping without reduction is said to have experienced:

Answer: Regulator failure (wide open)

A failed-open regulator passes full upstream pressure downstream, creating a serious overpressure hazard for piping and appliances.