ACS Tightness Testing & Purging

Question 1

Which instrument is typically used to perform a tightness test on a domestic gas installation?

Accepted Answer

U-gauge manometer

Answer

Electronic combustible gas detector

Answer

Digital pressure data logger

Answer

Rotary gas meter

Question 2

At what pressure should a tightness test be conducted on a domestic natural gas installation?

Accepted Answer

Working pressure (approximately 21 mbar)

Answer

75 mbar

Answer

50 mbar

Answer

100 mbar

Question 3

How long should the final tightness test period last after stabilisation for a standard domestic installation?

Accepted Answer

2 minutes

Answer

30 seconds

Answer

1 minute

Answer

5 minutes

Question 4

What constitutes a satisfactory result during a domestic gas tightness test?

Accepted Answer

No pressure drop at all

Answer

A pressure drop of no more than 2 mbar

Answer

A pressure drop of no more than 4 mbar

Answer

A pressure drop of no more than 1 mbar

Question 5

What is the purpose of the stabilisation period before the final tightness test reading is taken?

Accepted Answer

To allow temperature and pressure to equalise

Answer

To allow gas to escape to a safe background level

Answer

To allow the meter to begin recording gas flow

Answer

To allow the U-gauge fluid to reach ambient temperature

Question 6

What position should all appliance isolation valves be in during a tightness test?

Accepted Answer

Closed, isolating all appliances from the pipework

Answer

Open, to test the full installation including appliances

Answer

Half-open to allow controlled gas flow

Answer

Dependent on the type of appliance being tested

Question 7

Which of the following would indicate a failed tightness test?

Accepted Answer

The U-gauge shows a pressure drop during the test period

Answer

The U-gauge reading remains completely stable throughout the test

Answer

The gas pressure rises slightly during the test period

Answer

The meter registers no flow during the test