Teardown: Inside a one way valve, non-refillable valve gas cylinder 

i disassembled 3 and it was a success! i took the check valve out and now i got 2 air tanks in the car incase of a flat and the third one is filled with butane. butane doesn't make much pressure infact you could store it in a plastic bottle! i like baloon time tanks because of the weak point safety feature. if anything is gonna blow it will only make a loud pop and hiss. i use the butane tank to operate a camping stove, grill, heater. the butane is expensive in that amount to fill a baloon time tank but it lasts a very long time!

if you open the valve and not putting the nozzle, does the helium gas still goes out?

You are not alone in this world :)

I suspected my tank had a check valve since it was so hard to fill. I watched the "how helium tanks are made" video expecting to see how did they fill them but they didn't show that part. It's a very clever design. Thank you, can't wait to disassemble mine.

Many thanks for this. I've got a one here that I was thinking of using as a low-pressure tank for charging a very small pressure vessel that's a pain do using a pump. Looks like it's possible but not as easy as I thought. Fixing the poppet valve to the threaded part, say with pin in a new hole, should work.

thaaaaaaaaaank you so much Sir, I was breaking my head trying to decypher what the name of the nipple was, I'm stil trying to figure out if it is 1/4 size tho and if this is a special kind of thread or what. have a good one!

I couldn't remove that pesky T valve because they had knurled the threaded part over so it can't come out any further. Pliers!