Most dangerous

Cryo - oxygen, carbon dioxide, helium gas, hydrogen.... Cold, pressurized, and in some cases, unstable. As long as you take your time and follow procedure, it is all good.

I have also hauled caustic and acid, but cryo is some unforgiving stuff. You gotta be on your game at all times.

 

I hauled liquid oxygen for four years. That stuff will combust if it comes in contact with oil.

 

Combust and burn like 100 times the fires of hell. Add O2 in any fire and it gets hot, hot, hot.

Any petroleum product will react with LO2, including the stuff in asphalt. All load/unload areas have concrete pads, and vapor is shot into a stainless steel pan to eliminate ground contact.

 

Flammable/Combustible for LO2 and Hydrogen

Non Flammable gas for Co2, Ar, He, Ne, Kr/Xe

 

All can be in liquid, but some can be transported in gas form (tube trailers). He, H, Ne, Kr/Xe can be in either.

Class 2 - Non-Flammable gas for Ar, Co2, He, Kr/Xe, and Ne

Class 3 - Flammable/Combustible for H and LO2