How do I dispose of unused acetylene gas in a 40 cubic feet cylinder?

Answer 1

Sell it to a welding shop. Look in the Yellow Pages.

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Answer 2

Short of giving it away or just opening it up and letting the gas go you could try to local a store that sells gases like oxygen, acetylene, co2 and the likes, there is definitely one somewhere in your area since they supply the oxygen tanks to the fire/rescue departments. Just ask them whats the best thing to do or have them dispose of it for you.

Answer 3

sell it to a local compressed gas supplier,

or sell it to a local welding shop,
or let the local welding shop use it for free,

or burn it.

Answer 4

Why not keep it until it's all used, or give it to someone who can use it? There is no need to waste useful torch fuel.