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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

Appliances 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

Ignition Devices

  • Spark Igniters
    • Piezo-electric ignition
      • Fitted on gas fires, water heaters and older boilers
      • A plunger strikes crystal (quartz) and produces 6000v
    • Mains and electronic ignition
      • Uses step up transformer to create up to 10000v spark
      • Creates 4-8 sparks/second
  • Filament Igniters - small coil of thin wire which glows red when energized
    Filament Igniters
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Appliances Thermostats

  • Controls a burner when it reaches a pre-set temperature
    • Primary control - fitted within the appliance (controls heat input)
    • Secondary control - room thermostat
  • Operation types
    • With a pilot light - will close completely
    • With a by-pass - will keep a low flame going
Rod Thermostat
  • Invar rod (low thermal expansion) inside a brass tube connected at one end
Liquid Expansion Thermostat
Liquid Expansion Thermostat
  • Flexible metal bellows connected to a hollow probe by a capillary tube
  • It is full of either a gas or liquid
  • The stat for a cooker has a by-pass tube
Electrical Thermostat
  • Do not pass gas through their body
  • Solenoid Valve is used to control the gas flow
  • Bellows operated device - the most common
  • Bimetal coil - room thermostat
  • Bimetal strip - cylinder thermostat
  • Should be checked using continuity testing (avoid live test)
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