Here you can find useful links to resources and data.
Air Liquid has a good site for physical properties of gases and phase conversions
European Industrial Gases Association. Central organisation which publishes useful documents on gas safety and technology.
A site for heat treatment processes, gas analysis and supplying gas systems.
An interesting site for what is going on in the global industrial gas world. If you need a used ASU you might find it here.
Here can you find interesting information about state of the art combustion technology with low NOX emissions for heating furnaces.
When you need to convert physical units, this site is quick and free.