GPT System Inspection & Maintenance 4

Question 1

According to NFPA 54, what is the maximum allowable pressure drop across a house line piping system supplying appliances at low pressure (under 2 psi)?

Accepted Answer

0.5 in. w.c.

Answer

NFPA 54 limits pressure drop to 0.5 in. w.c. for low-pressure systems to ensure appliances receive adequate delivery pressure.

Question 2

A gas technician is inspecting a meter set and notices the meter index is turning when all appliances are off. What does this indicate?

Accepted Answer

There is a leak downstream of the meter

Answer

A moving index with zero appliance demand means gas is flowing out somewhere — a downstream leak is the probable cause.

Question 3

What type of joint is prohibited for use on gas piping inside a building when the pipe passes through a wall or floor?

Accepted Answer

Mechanically coupled (Dresser-type) joints

Answer

Mechanically coupled (Dresser-type) couplings are not approved for concealed or through-wall gas piping because they can loosen over time.

Question 4

During a maintenance inspection, a technician discovers that the gas vent pipe on a water heater has a negative pitch (slopes back toward the appliance). Why is this a defect?

Accepted Answer

It allows condensate to pool and can obstruct flue gas exhaust

Answer

Vent pipes must rise continuously to the outside; a backward slope causes condensate to collect, which can block the vent and allow combustion gases into the building.

Question 5

What is the correct procedure for relighting a standing pilot on a gas appliance after a maintenance shutdown?

Accepted Answer

Follow the manufacturer's lighting instructions, ensuring the area is purged of gas first

Answer

Manufacturer's instructions ensure safe pilot lighting sequence, including purging any residual gas to prevent a flash ignition.

(GPT) Gas Pipe Technician Certification Practice Test

(GPT) Gas Pipe Technician Certification Practice Test

GPT System Inspection & Maintenance 4