ACS Pipework & Meters

Question 1

What colour is the MDPE (medium density polyethylene) gas service pipe used underground in Great Britain?

Accepted Answer

Yellow

Answer

Yellow MDPE is the standard colour for gas service pipes installed underground in the UK, distinguishing them from other buried utilities (blue for water, black for electricity).

Question 2

What is the function of the Emergency Control Valve (ECV) on a gas installation?

Accepted Answer

To isolate the entire gas supply to a property in an emergency, located immediately upstream of or adjacent to the gas meter

Answer

The ECV (quarter-turn cock) is the master isolation valve for the property's gas supply, used in emergencies to cut off all gas and by engineers before carrying out gas work.

Question 3

Which type of fitting is used to join copper gas pipework in domestic installations and does NOT require soldering?

Accepted Answer

Compression fittings or press-fit fittings

Answer

Compression fittings and press-fit fittings mechanically join copper pipe without heat, reducing fire risk during installation and making them suitable for use in occupied buildings.

Question 4

What is the purpose of a gas meter index reading?

Accepted Answer

To record the volume of gas consumed at the premises, forming the basis of the customer's gas bill

Answer

The meter index records cumulative gas consumption (in cubic metres or cubic feet); billing is based on the difference between successive readings multiplied by the calorific value of the gas.

Question 5

What does 'pipe sizing' involve when designing a domestic gas installation?

Accepted Answer

Calculating the correct pipe diameter to supply the required gas flow rate to all appliances simultaneously without excessive pressure drop

Answer

Pipe sizing uses gas rate demand, pipe length, number of fittings, and permissible pressure drop tables (BS 6891) to select pipe diameters that ensure adequate gas pressure at all appliances under simultaneous load.

Gas Safe ACS Practice Test

Gas Safe ACS Practice Test

ACS Pipework & Meters