G3 Leak Detection and Testing Procedures 2

Question 1

Electronic combustible gas detectors measure gas concentration as a percentage of which value?

Accepted Answer

Lower explosive limit (LEL)

Answer

Maximum allowable operating pressure (MAOP)

Answer

Upper explosive limit (UEL)

Answer

Stoichiometric combustion ratio

Question 2

What type of electronic leak detector is best suited for detecting very small leaks in high-pressure gas distribution mains?

Accepted Answer

Flame ionization detector (FID)

Answer

Catalytic bead sensor

Answer

Thermal conductivity sensor

Answer

Photoionization detector (PID)

Question 3

Under CSA B149.1 Natural Gas and Propane Installation Code, which test medium is NOT acceptable for leak testing gas piping?

Accepted Answer

Oxygen

Answer

Natural gas

Answer

Nitrogen

Answer

Air

Question 4

When using an electronic leak detector in a confined space, the technician should check gas concentration at which level first?

Accepted Answer

It depends on the specific fuel gas being tested

Answer

At floor level, since all fuel gases are heavier than air

Answer

At ceiling level, since methane (natural gas) is lighter than air

Answer

At mid-height where mixing occurs

Question 5

A G3 technician is called to a suspected gas leak. What is the FIRST action upon arriving at the scene?

Accepted Answer

Eliminate all ignition sources and ventilate the area

Answer

Begin leak testing with electronic detector immediately

Answer

Call the gas utility to shut off supply

Answer

Apply soap solution to all visible pipe joints

Question 6

Which instrument is used to measure gas pressure with the highest accuracy for low-pressure systems operating at or below 14 in. W.C.?

Accepted Answer

Slant-tube manometer

Answer

Bourdon tube pressure gauge

Answer

Manometer (water column gauge)

Answer

Digital compound gauge

Question 7

When testing a gas system that has been out of service for an extended period, why must the system be purged before returning to service?

Accepted Answer

To displace air or inert test gas that could create a flammable mixture at the burner

Answer

To remove moisture and debris from the piping

Answer

To increase the system pressure to operating levels

Answer

To reset all pressure regulators to factory settings