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

3 in. w.c.

Answer

1 in. w.c.

Answer

5 in. w.c.

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

The meter is malfunctioning and needs calibration

Answer

The meter bypass valve is open

Answer

Normal thermal expansion of gas in the line

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

Welded joints

Answer

Press-fit joints listed for gas

Answer

Flanged joints

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

It increases the draft efficiency

Answer

It creates excessive back-pressure on the burner

Answer

It violates clearance-to-combustibles requirements

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

Open the main gas valve and ignite immediately

Answer

Wait 5 minutes after detecting gas, then light with a match

Answer

Set the thermostat to maximum to force ignition

Question 6

A gas technician finds that a ball valve handle has been painted over and is stuck in the open position. What is the correct course of action?

Accepted Answer

Remove the paint obstruction, verify operability, and replace the valve if it cannot operate freely

Answer

Apply penetrating oil and force the valve closed

Answer

Leave the valve in place and paint it a different color

Answer

Install a second valve downstream as a workaround

Question 7

Which of the following pipe materials requires dielectric unions when connected to dissimilar metals in a gas system?

Accepted Answer

Copper to black steel

Answer

Black steel to black steel

Answer

CSST to CSST

Answer

HDPE to HDPE