Chromatography Forum

What is the diffrent between liquid sampling valve (LSV)and gas sampling valve (GSV)

What is the diffrent between liquid sampling valve (LSV)and gas sampling valve (GSV)

The difference is very similar as between a water tap and a gas tap.

Fundamentally, they are the same. They would both be used to divert a sample stream to some container for collection or to a chromatograph for analysis.

I have rotary-injection valves mounted inside the oven of a GC so that I can fill the loops (0.5 mL) with gas, vent the lines down to atmospheric pressure, then make injections of that gas into the GC by rotating the valves so that the carrier gas passes through the loops. In my case, I separate the same gas mixture on 2 different columns. Venting to atmospheric pressure before injecting helps to improve the precision of the sample introduction into the chromatograph.

It is likely that you would not be able to use that same system to inject liquids into a GC. Too much solvent present. It is a splitless injection technique.

The basic difference is that due to the sample size that needs to be injected into the GC, a gas sample valve has the sample loop external to the valve, whereas the liquid sample valve has the 'sample loop' machined into the rotor. The LSV on a GC is usually used to inject a liquefied gas.

Gasman

LSV's sample at high pressures and low temperatures (typically) while GSV's (typically) sample at low(er) pressures and can be used at higher temperatures.

Best regards,

AICMM