Master Plumber Exam Gas Piping Systems 3

Question 1

A sediment trap (drip leg) on a gas appliance connection must be installed:

Accepted Answer

Immediately upstream of the appliance inlet, after the shutoff valve

Answer

The sediment trap must be located immediately upstream of the appliance to catch debris before it enters the appliance valve.

Question 2

Which gas pressure range is classified as 'intermediate pressure' under NFPA 54?

Accepted Answer

2 psi to 5 psi

Answer

Intermediate pressure gas systems operate between 2 psi and 5 psi according to NFPA 54 classifications.

Question 3

When a gas pipe passes through a concrete floor slab, it must be:

Accepted Answer

Sleeved in a conduit sealed at both ends

Answer

Gas piping through concrete must be sleeved to protect the pipe from corrosion and allow for movement without cracking.

Question 4

What is the purpose of a pressure regulator on a gas system?

Accepted Answer

To reduce and maintain stable downstream gas pressure

Answer

A pressure regulator reduces higher upstream pressure to a stable, lower downstream pressure suitable for appliances.

Question 5

Under the International Fuel Gas Code, gas piping is NOT permitted to be run through which location?

Accepted Answer

Elevator shafts or dumbwaiter shafts

Answer

Gas piping is prohibited in elevator shafts, dumbwaiter shafts, and similar enclosed shafts due to the severe fire and explosion risk.

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