On a standard installation gas is piped up to the inlet of the system where there will be a manual isolation valve. A pilot/ignitor off-take is next in line to take the gas for the pilot and ignition system. This line is sized at 25NB and will contain a small flame arrestor before splitting into two separate lines:
The first line is the pilot line and will normally start with two solenoid valves in-series and carry on through an air injector to provide the correct gas/air mix into the pilot tip. The pilot line will either be at the top of the stack on an elevated system or inside the chamber at ground level on a ground flare.
The second line is sized at 40NB and is the ignition line. This starts with an air injector to set a correct gas/air mix and a spark plug shortly after to ignite the mix.
Flare Products’ unique ‘flashtube’ system for ignition enables a small ball of flame to be ignited and travel along the ignition tube to the pilot tip where it lights the pilot.
In the main line after the off-take point there will normally be twin in-series, failsafe, automatic, electrical shut off valves. These control the gas flow to the burners. Prior to the burners is a flame arrestor. In the event of a flashback this mechanism prevents any flames from coming back down the line. The arrestor contains an S.S. element. Gas will then either enter the combustion chamber manifold or stack depending on system type in use.