Chromatography Forum

Dear all,
I'm looking for a connection between the deep tube CO2 cylinders to swagelok for liquid CO2 which is used to cool down a PTV injector. Classic regulator are problematic as they decrease the pressure and also freeze. Did you know were I can purchased such system?

Thanks in advance. Best regards.

Are you using a heated regulator?

http://www.praxair.com/praxair.nsf/7a11 ... enDocument

I'm not sure of your instrument, but some instruments accept the full pressure from the cylinder eductor tube, as they want liquid to be at full pressure at the cooling nozzle in the instrument..

Some gas companies ( eg BOC ) sell inline heaters that can be used to warm the liquid CO2 before it goes to the regulator, provided you want gaseous CO2 at lower pressure.

Please keep having fun,

Bruce Hamilton

Ortelli,

Maybe I don't understand the problem, but why are you using a regulator at all. The CO2 systems I have seen go straight from cylinder to GC, no regulator, just a shut off valve.

Best regards.

Hello AICMM,
thanks for your reply. My problem is not that I want to use a regulator. It's just that I don't know how to connect my 1/16" tube to the CO2 cylinder.

OK, 1/16" tube suggests you want a direct connector to the liquid CO2 cylinders eductor tube. Basically, you also want an inline particulate filter that can handle 1000+psi, as dirt can quickly block the fine cooling nozzle.

Swagelok sell all the necessary filters and fitters. The filter should have a fine ( eg 7um ) Stainless steel sinter element with 1/8" or 1/4" fittings - depending on the line from the cylinder.

There are various Swagelok adapters ( reducing or expanding ) on lines up to the thread that will be on the cylinder connection fitting, which should be provided by the gas cylinder company, and which may have either and ISO or NPT taper thread thread, for which Swagelok also has adapters. Taper threads require threadseal tape, parallel threads don't.

As the cylinder pressure is around 800psi ( or more if it has He headspace pressurisation ) , you may require certified fitters and/or safety extras, such as an isolation valve with high pressure vent or bursting disk, depending on your building codes.

I'm very surprised that your instrument manual doesn't detail suitable requirements.

Please keep having fun,

Bruce Hamilton

So that you keep the CO2 liquid all the way to the expansion nozzle you need to keep the 1/16 inch tube as short as possible to minimize pressure drop. I have used 1/8 inch tube in the past for this reason.

Peter