CO2 bottles

[Gasbot]

Hello guys,

I'm in need of a bit of help from the collective. I've got a pair of old CO2 bottles (4 outside dia ones) which oddly enough fit perfectly into my chassis. The newer shorter fatter CO2 bottles simply won't fit into the space I have available. I would like to get my hands on some new bottles but I don't think they are available to buy any more. To my untrained eye my bottles look good (there is some cosmetic damage in the paint) but they are well out of their test date, so my questions are:

1. Does anyone know where I can get hold of 4 dia CO2 bottles for reasonable money?
or
2. Can I get these bottles hydro pressure tested and certified by a local workshop?

But assuming the worst:
3. Can I manufacture my own cylinders and get them tested (I'll use the valve & burst disk etc from the bottles)

Ta.

[blazerbotics]

You might be able to get them tested, i've used http://www.jacksonkeay.com in the past for mine. What weight/capacity are the bottles?

[Gasbot]

Doh forgot to mention they are of the 2Kg Co2 variety.

[Gasbot]

Ok so the man from Chubb had a look at the bottles and said something along the lines of how old they are and that he'd scrap them because the handles were 'broken' (I cut them down to fit)... not much help really.

Alan I tried calling the company you mentioned but nobody answered the phone.

So what would be my options now. The bottles I have show a design pressure of 55 Bar and a Test pressure of 200 Bar, if I get them hydro tested to 200 bar along with a certificate will they be accepable for use? Alternatively can I design my own bottles for 55-70 Bar and hydro test them to 200 Bar? The burst disk is set at 190 bar if I'm not mistaken so this should rupture before the tested pressure is exceeded. Would there be any problems doing this? Obviously they wouldn't be BS stamped but I can get them made in accordance with ASME which I hope would be sufficient.

Sorry for the weird questions but I really need some 100mm diameter bottles. Sadly a pair of 105mm or 117mm bottles wont fit. A single bottle is an option if I really have to, but using two is my preference.

[woody]

The condition of the fittings has nothing to do with the bottle plus they're supplied after testing with new valves.

[kane]

9.3 Cylinders
The compressed gas shall be stored in a commercially manufactured gas cylinder of appropriate design,
specification and certification. Except where the maximum storage pressure is less than 50psi (3.4bar).
Some events may have further restrictions on bottle sizes/ weights used, please contact the event organiser
for clarification.

Most people use the 2Kg Aluminium CO2 bottles with screw valves fitted. I would recommend adapting your design to use the newer bottles that are easier to get hold.
Of course if you are able to get your current bottles re-certificated then that would also be acceptable.

The thinner bottles tend to be steel and these can corrode quite badly over time resulting in failure, especially if moisture has been allowed into the bottle (e.g. valve left open for period of time).

[maddox10]

Hello guys,

I'm in need of a bit of help from the collective. I've got a pair of old CO2 bottles (4 outside dia ones) which oddly enough fit perfectly into my chassis. The newer shorter fatter CO2 bottles simply won't fit into the space I have available. I would like to get my hands on some new bottles but I don't think they are available to buy any more. To my untrained eye my bottles look good (there is some cosmetic damage in the paint) but they are well out of their test date, so my questions are:
2. Can I get these bottles hydro pressure tested and certified by a local workshop?

If a bottle is 20 years old, nobody will recertify.

1. Does anyone know where I can get hold of 4 dia CO2 bottles for reasonable money?

Doubtfull. Last time I bought 2 new bottles with screw valves I coughed up £120 each.

But assuming the worst:
3. Can I manufacture my own cylinders and get them tested (I'll use the valve & burst disk etc from the bottles)

Yes, but no firm will certify a welded mobile storage bottle.
Maybe if you have the welds seperatly certified by Rntgen pictures, and have the certification sheets of the used material.

And even then, there is a small problem.

9.3 Cylinders
The compressed gas shall be stored in a commercially manufactured gas cylinder of appropriate design,
specification and certification. Except where the maximum storage pressure is less than 50psi (3.4bar).
Some events may have further restrictions on bottle sizes/ weights used, please contact the event organiser
for clarification.

[Gasbot]

Thanks for the replies.

We make industrial pressure vessels for a living so design & thickness calculations, coded welding, 100% radiography and dye pen examination isn't really a problem. Not a problem though, we'll cross our fingers and try to track down something suitable.

Ta.

[maddox10]

If you have acces to that kind of infrastructure and services, why not help other roboteers getting their stuff certified?

[team_mute]

Above questions were all about Mute's bottles as we are trying to get it working again, but the bottles are well past test date, so you can see why we are stuck with 4 dia ones. Hopefully we've found some that are only a little bit bigger and weight the same.

With regards to pressure vessels, we make stuff to ASME design and covered with PED. The cost for this compared to an off the shelf, mass produced CO2 bottle would be a bit different.

Also Im guess a couple of special tanks on the market wouldn't be a problem for tech checkers but if everyone had one it would be a nightmare to check.

Hopefully see you all soon

Adam