COMPRESSED AIR, & AIR, REFRIGERATED LIQUID

The biggest difference between compressed air and Refrigerated Liquefied Air is the oxidizing property of the later, IMDG Code lists both as :

UN 1002 AIR, COMPRESSED               Class 2.2

UN 1003 AIR, REFRIGERATED LIQUID Class 2.2 with subsidiary risk 5.1 (oxidizing agent)

Compressed air locomotive
Compressed air locomotive (Photo credit: Wikipedia)

 Observation for UN 1003 in the IMDG Code states “Liquefied, non-flammable gas.Strong oxidizing agent.Mixtures of liquid air with combustible materials or oils may explode. May ignite organic materials”.