[Ice Czar]

Acetylene

Due to the carbon-to-carbon triple bond, acetylene gas is fundamentally unstable, and will decompose in an exothermic reaction if compressed to any great extent. Acetylene can explode with extreme violence if the pressure of the gas exceeds about 100 kPa (≈14.5 psi) as a gas or when in liquid or solid form, so it is shipped and stored dissolved in acetone or dimethylformamide (DMF), contained in a metal cylinder with porous filling (Agamassan), which renders it safe to transport and use.

History - Acetylene dissolved in acetone

In 1896 the French scientists Claude and Hess discovered a way to store and transport acetylene without the risk of explosion. This method is based on the fact that acetone can dissolve many times its own volume of acetylene. The French call acetylene dissolved in acetone acétylène-dissous. At a pressure of 10 atmosphere one liter of acetone dissolves approximately 250 liters of acetylene.

But the near-accidents continued. Claude and Hess filled the containers with a porous compound which formed a system of small capillaries. The compound was drenched in acetone and then filled with acetylene. Since an explosion cannot spread in a tube with a diameter of a fraction of a millimeter, the inventors considered the problem solved. But the compound failed to meet expectations. Over time large holes could appear and explosions could occur.

Pennsylvania Dept of Environmental Protection , Deep Mine Safety, Oxy-Acetylene Safety Awareness ppt

it is an unstable gas, will violently decompose when in a pure state above 15 psi

Auto-ignition temperature is 763-824F, this means if Acetylene reaches 30 psi in a free state, it can explode by itself without a spark or flame being present

the firebrick also helps by minimizing the free volume of the cylinder, cooling and controlling any thermal decomosition before it gets out of control (each decomposition of acetylene gives off heat)

porous filler 8-10%, Acetone 42% Acetylene 36%
Must always be stored upright, this prevents the acetone and acetylene from seperating

Acetylene, the Principles of Its Generation and Use by Butterfield and Leeds - Project Gutenberg