The use of the term Inert Gas is a misnomer in so far as the true inert gasses such as Helium and argon are prohibitively expensive to use.
Similarly the use of semi-inert gasses such as Nitrogen and Carbon-dioxide are too expensive to use on bulk, nitrogen is often seen in use on gas carriers in barrier spaces or for the clearing and inerting of pipelines and pumps.
The gas most commonly used is the exhaust product of combustion.
- This may have three sources
- Exhaust from an internal combustion engine such as a diesel engine or gas turbine. The relatively high Oxygen content in the output must be reduced to make it suitable and this is generally achieved by the use of an afterburner. This is an uncommon system and will not be dealt with currently
- Gas oil or heavy oil powered inert gas generator. This generally takens the form of an insulated combustion space similar in layout to a tank boiler with the insulation taking the place of the water,with rotary cup burner
Purging- This is the introduction of inert gas into an inerted space to;
- further reduce O2 content
- reduce hydrocarbon level in the inert gas so that air may be introduced without the mix entering the flammable range.