Does anyone transfill their tanks?

[weldingtwopotatoes]

I just bought a new 80cf argon tank because I was getting screwed on the refill charges on the 20cf tank (25$ to refill the 20cf and only $30 to refill the 80cf). I do like the portability of the 20cf tank though and I was thinking of just transfilling the 20cf from the 80cf. Does anyone on this board transfill their tanks and how do you go about doing it?

[junes]

Don't bother it's not worth it's alot easier just to get it filled you need a few tanks to transfer fill to any high pressure why do you want to anyway

[weldingtwopotatoes]

I want to transfill it do save the money on filling it and to have it for its portability. About 2 months ago I took the tank to a welding supply to swap it out but the guy said that he didn't have any tanks to swap out at that time but he told me he could transfill it. I said ok and all he did was hook up a regulator looking thing up to a larger tank and filled my small tank. I didn't get a good look at the regulator thing and I don't know if it is something special. He didn't use mutliple tanks he just filled directly from the larger tank and is was real easy. I just want to do what he did just at home.

[KHK]

I have a transfer tube for oxygen and have used it many times in the past. The one that I have is a comercialy made set up. It is a rube that is rated at 5,000 psi with the proper fittings on it. I have not used it in many years and wanted a locial welding supply to test it before I put it into service again. They would not test it for me. I don't know if they were not set up to test it or what. Due to the high pressire involved I would NOT make my own. The possible personial injory or death is not worth it.

[weldingtwopotatoes]

I was just trying to figure out what he was using, I wish I got a better look at it. I would prefer not to build my own but I figured somebody out there I'm sure has and I wonder what they used to make it. What does the tube look like on your oxygen one and does it have markings?

[ksmeggy]

You should be able to do this with the right tubing and adaptors. The only gas I know of that has safety issues with pressure/temperature is acetylene (I seem to recall acetylene tanks are refilled in a 'cascade'-type setup).

Argon is an inert gas, it should obey the ideal gas laws exactly. Of course I don't remember what those are, I just know you're dealing with standard pressure/volume/temperature relationships; expand the gas, it cools; compress it, it heats.

[KHK]

I was just trying to figure out what he was using, I wish I got a better look at it. I would prefer not to build my own but I figured somebody out there I'm sure has and I wonder what they used to make it. What does the tube look like on your oxygen one and does it have markings?

The charging hose that I have is a teflon reinforced tubeing with the proper ends on it. It will work on all of the inert gases. There are no markings on it.
The problem in charging is the pressure. If the tubeing happened to repture there could major problems.

[junes]

Acetalyne is only stable by itself at around 15 psi anything beyond that is a crap shoot at best so they store it in an acetate cotton form and since it is soaked up in this cotton type material it is stable at pressuresaround 300 psi or so. The cylinders anr actuallyin two pieces. It's just not worth the hassel of transfer filling I have a 60 and a 330 at my house alone and I don't transfer it extreamly incovienemt.

[jbman45]

First, don't mess with acetylene. As stated on other posts it is dangerous and should only be filled to tanks that have the acetone content checked, higher pressures with too little acetone to absorb the CH3 will reslut in an explosive container.

For other containers, argon; nitrogen, mixed gasses you can transfill but it's not efficient unless you use a cascade system with a minimum of three bottles. So you can do it but you'll have to cascade it like they do with scuba tanks and work your way up to the higher pressures. Lots of work for ??

[weldingtwopotatoes]

This was never about transfilling Acetylene. I don't have a death wish. I'm fully aware of the special requirement for Acetylene.


For the purposes of my question this is only to do with Argon. I know it can be done easily as I have seen it done, directly from a larger tank to my tank. I would go back and ask the guy except that would be kind of weird considering that's where I get my tanks filled. I just don't like the premium charged on smaller tank refills and thought someone might have a simple way to get around that. I appreciate the responses though.