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Gas Safety

Exam revision materials for Plumbing Level 2&3 and ACS Gas Safety test

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Safety Devices and Controls

Gas Meter Controls

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Safety Devices and Controls

Air/Gas ratio valves

Appliances Controls

Flame Supervision Devices FSD

Gas Controls

Gas Meter Controls

Safety Cut-off Devices

Spare Part Identification


Open-vented System


Gas Appliances

Ventilation Sizing

Unsafe Situations

Dealing with Unsafe Situations

Emergency Notices and Warning Labels

Gas Leak




Tightness Test

Gas Performance

Gas Rate

Heat Input

Gas Supply

Gas Meters

Gas Pipework

Gas Fittings and Pipes

Gas Supply


New Installation

Pipe Protection

Pipework Sizing

Chimney and Flue


Flue Construction

Flue Inspection and Testing

Flue Terminals

Flue Types


Carbon Monoxide Poisoning

Combustion Process

Natural Gas

Portable Combustion Gas Flue Analysers


Components and Safety Devices

Emergency Control Valve ECV

Emergency control valve ECV
  • Normally is the property of the gas supplier
    • Who has to maintain and lable it
    • Notify gas supplier if ECV is faulty
  • ECV should confirm to BS1552
  • 'Nitting' - plug stops in the fully on or off position
  • Must be where the pipe enters the building
  • Must have an on/off indicator label
  • The handle must stop the gas in its lowest position
  • A label naming who to contact in an emergency nearby (usually on the meter)
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Medium to Low Pressure Governor (Regulator)

Medium to low pressure regulatorMedium to low pressure regulator
  • 2bar pressure reduces to 21mbar operating pressure
  • Its sealed by the gas supplier and set at 19-24mbar
  • Governor Lock up - closes when pressure builds up (24-28mbar)
  • Most appliances have their own regulators (governors)
  • Incorporates
    • Overpressure protection (OPSO)
    • Under pressure protection (UPSO)
    • Excess flow device - prevents UPSO being reset if there are open ends downstream of the regulator
  • Testing
    • Let-by and tightness test in accordance with IGE/UP/1B
    • Working pressure test - with 3 bigest hobs ON on a gas cooker
    • Standing pressure test
    • Under pressure shut off (UPSO) test
    • It should not be possible to to reset the UPSO until all control taps have been closed
  • Checks
    • Only authorised by gas supplier operaive can break the seal
    • Adjust the outlet pressure periodically
    • Leather diaphragm (old appliances) may need lubricating
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