By: Rutterbush
The inside of an acetylene cylinder.

This is the cut away training cylinder that I use at the college of welding knowledge. The white product inside of the cylinder is called a monolithic material. That is a non-name. I haven't discovered a definition for it yet, but I'm still trying. The monolithic material is very porous and reminds me of sheet rock gypsum. The monolithic material is soaked in acetone. Acetone is a liquid solvent that will dissolve acetylene gas. This dissolving action stabilizes the acetylene so that it can be pressurized in the cylinder. Without the acetone and the monolithic material the acetylene is unstable and can self ignite and/or explode above 15psig in the free state. A hard blow to the side of the cylinder can move this monolithic material and allow the acetylene gas to dissassociate, or separate, from the acetone and collect under pressure in this hollow. This will allow the acetylene to violently decompose which causes the cylinder to explode.