Chromatography Forum

Hello,

I wonder if some of you have experience with use of a inert gas mixture at P of 200 bar or above (and maximum limit) with a Rheodyne 7725 liquid valve or if you see any problems to use a liquid valve as a gas valve on these conditions?

Many thanks in advance

Adão Araújo

Portugal

Ask Rheodyne.

My only concern would be the lower viscosity would allow gas to creep through crevices, so ensure the valve is in good condition and all bolts have been tighened to ensure really good contact, and switching is performed rapidly.

If possible, try to allow the valve to sit at low pressures when not being used to reduce chances of gaseous tracking.

Bruce Hamilton

Thank you Bruce,

I wonder if you know other alternatives besides Rheodyne. I'm also asking them anyway and hope I can have an answer.
6 way valves in our market are not so common and our only source is Rheodyne.

Best Regards

Adão Araújo

You can get 6 port valves for GC use from Valco instruments. Their agent in Portugal is as follows.

Paralab LDA

Phone (+351) 22 466 43 20
Fax (+351) 22 466 43 21

Gasman

Thank you for your answer.

I need valves for HP till 200 bar and above. I know that VICI also has this valves but limited in P rabnge till 60 or 80 bar. Sure I can use their valves for this purpose?

Best Regards

Adão Araújo

You should contact Valco. They will also need to know the temperature that you will be working at. I have supplied gas sampling valves from Valco that go to 5000 psi (344 Bar).

Gasman