Hello,
I would like to make an automatic control of a pressure gradient in a capillary, which is needed to get molecules from a furnace to a mass spectrometer. Could you help me how can I make an automatic connection of valves? I always have to manually adjust them to get right pressure in a capillary. I have to deal with 2 different pressure conditions in the furnace:

1. atmospheric pressure (40 mbar in a capillary)
2. 40 mbar (1.10-3 mbar in a capillary)

(see the scheme: http://www.berger.euweb.cz )

Both conditions needs to be treated by adjusting valves to regulate a vacuum pressure in a capillary made by rotary vacuum pump. This pump helps to reach a pressure gradient between the furnace and the mass spectrometer equipment.

Actually I think that the valve close to pump is the one which should be regulated. The valve close to the furnace should be probably changed for pressure transducer sending an informatin to the valve by the pump.

Could you make any suggestion how I could make an automatic valve switching for both pressure conditions?

Thank you for any helpful notes.

 

I assume you have some form of pressure transmitter to measure the pressure and your GC runs on a PC. I have attached a link to a valve actuator vendor.
http://www.hanbayinc.com/

This company makes small actuators that fit the tiny instrument valves. Some of these have a serial interface to work with a PC. If you fit one to the valve you presently change by hand you may be able to automate it using the GC's PC. I think Hanbay would also be helpful in recommending a software package.

Hope this helps,
Roy

 

Thank you very much, I think that I can order some valves with actuators on that website.

Stan