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Gas Safety

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

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Gas Performance

Gas Rate

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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

Gas Rate Check

  • amount of gas being burned by an appliance
  • whether an injector is blocked or oversized
  • 5% tolerance is allowed against the data badge readings on the appliance
Convert ft3 into kW
  • 1 m3 = 35.336 ft3
  • 1 unit of gas (100 ft3) = 2.83 m3
  • Calorific Value = 38.5
  • kW = (reading in ft3/100) x 2.83 x 38.5/3.6(const.)
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Calorific Value (CV)

  • Calorific Value - the volume of gas consumed by the appliance in one hour
    • Natural gas - 38.6MJ/m3 Gross or 1040btu/ft3
      • net = gross/1.1
    • Propane average - 93.1MJ/m3 Gross or 2694btu/ft3
      • net = gross/1.09
    • Butane average - 121.8MJ/m3 Gross or 3265btu/ft3
      • net = gross/1.08
  • 1kW = btu/3412
  • Wobbe Number - is an indication of heat produced from a burner:
    • WN = CV/√SG(Specific gravity)
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