What is the solid material inside an old acetylene tank?

Question

It looks like asbestos.

Answer 1

Diatomatous earth, Chalk like material. It is a mineral made from Diatoms, Microscopic fossils. Just like the White Cliffs of Dover in Great Britain. The Acetylene is held held in solution by Acetone.The acetone is soaked up by the Diatomatous Earth Free Acetylene is explosive at around 23 psig. But having it in solution the volume of the fuel gas can be placed under pressure. That is why the fuel gas regulator has a Red Line, so you do not release the free acetylene over the 15 psig. Commercial Divers if they are using a fuel gas torch underwater use a Hydrogen torch. Because they then can set their gages safely to compensate for over bottom pressures needed to be able to effectively cut.

Answer 2

Acetylene is outrageously explosive with a wide range of oxygen mixtures and under various pressure conditions.  The material dissolves massive amounts of acetylene and releases it at uniform pressure to provide even flow and much greater safety.  

acetone holds the gas and is soaked on the material

http://www.metalwebnews.com/howto/weld/w...

"acetone saturated plaster."

http://en.allexperts.com/q/Welding-3487/...