Port valves

[bsxenia]

Hello!!

I am going to make some experiments on permeation of gases through polymer membranes and I will use a 6 port valve. But I don't know exactly how I could make the selection of that valve. I have already seen that commercially are available a lot of products. Except the temperature and the pressure, the other options of standoffs etc, how can select.
Any ideas??
Thank you i advance.

[GasMan]

You should contact the manufacturer of your GC. They should be able to tell you what to order. If you wish to build the valve into the GC, you basically must go with the manufacturer. If you wish to build it 'outside' of the GC, then you must decide on how you wish to actuate the valve, manually, with electric motors or with air actuators. Again, you are dependent on the type of GC that you have , as this will also make the choice of automation of the valve limited.

To get more help, you should post the type of GC that you have and what this valve is supposed to do.

Gasman

[bsxenia]

The GC that I have is from VARIAN 3800 with a capillary column. I want to built outside the GC a six port valve with two position and to actuate with an electric motor or microelectric. But I think I have an idea of the size that the port should have and the fittings. Also, if I want to control the temperature in the valve port, I should put it in a heated enclosure, because I want to analyse gases. Am I right?

[GasMan]

If the gases have a boiling point lower than room temperature, you do not need to heat the valve. Most people use valves with 1/16 inch ports. I am only familiar with the valves from Valco. The electric actuators need two contacts to operate them, one to switch the valve on and one to switch the valve off. I am not familiar with the Varian 3800 GC, so I do not know what contacts they have available.

You will also need to know what concentrations you will have for the gases. If they are too high for the capillary column, you will need to split the sample. This will determine where you connect the valve into the carrier gas line. If you are not familiar with gas analysis, it might be useful to tell us what gases you are trying to measure, then the forum can advise you on what column or columns to use.

Gasman

[AICMM]

bsxenia,

You can run the valve body directly inside the GC if you don't plan on taking the GC oven too hot. This eliminates the need to buy a separate valve oven and heater. You simply use a long enough stand off to hold the valve inside the oven and the actuator outside the oven. You certainly want a valve with 1/16 inch fittings since you can buy ferrules that will connect your capillary column directly to the valve.

Best regards.