If acetylene was stored as a plain ole' compressed gas, like oxygen or argon, then no sweat.
Originally Posted by BigEd_36
Because acetylene is stored saturated in acetone in a porous filler inside the tank, the possibility exists (probabilty, actually) that attempting to withdraw the gas at pressures lower than 15 PSIG will result in liquid acetone being drawn from the tank.
The same thing may happen if you try to draw more than 1/7 of the tank volume out per hour. Here's a read:
Acetylene (C2H2) as packaged for welding is safe if handled correctly and used as intended. Acetylene becomes very shock-sensitive when compressed to pressures greater than 25 PSIG. To allow storage at higher pressures, welding acetylene tanks are filled with a porous “sponge” which is saturated with liquid acetone. Acetone will absorb acetylene gas at a rate of 1/7 of its volume per hour. The solution of acetylene in acetone is stable at higher pressures. It takes 7 hours to fill an acetylene tank.
By the same token, the gas can only be withdrawn from the tank at the same rate as it was filled. Attempting to withdraw greater than 1/7 of the tank volume for more than a few minutes will result in liquid acetone being withdrawn from the tank. Liquid acetone will quickly eat away the diaphragm of the acetylene regulator, allowing liquid acetone at full tank pressure to enter the hoses and torch.
Acetylene discharged into air (or an oxygen/acetylene torch) at pressures greater than 15 PSIG may cause the gas molecules to disassociate, resulting in free hydrogen gas, which is highly explosive. That’s why the “red line” on acetylene gauges is 15 PSI!
When transporting acetylene tanks, they should remain upright. If they are laid down for any reason, they should be allowed to remain upright for at least 30 minute before use.
When deciding what tips or multi-flame (rosebud) heating nozzles to use, be sure that the hourly consumption rate in cubic feet does not exceed 1/7 of your tank volume. Large (#8 and larger) usually require a manifold array of acetylene tanks to provide the required volume.
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