Hydrogen generator

[allene]

Hi all,

My GC FID detector extinguish after ignition. The H2 flow is 1 ml/min (set value= 30 ml/min), so I think there is no flow from hydrogen generator. Apparently generator works well: the pressure of H2 is 3.2 bar and no fault is showed in its display, but I have no H2 flow to the GC.

My hydrogen generator mark is "Claind" ( H2, N2 and Air generator combination) and has been off for 2 years.

Any help will be greatly appreciated.

[Consumer Products Guy]

If it's Agilent GC, change the Lit Offset setting.

[alcorn]

It's a Varian 3800 GC.

[rb6banjo]

So, you can light the detector and it will stay on but it goes out when you make an injection? What is the outlet pressure of the H2 generator?

[Peter Apps]

First step, check whether the flame really is burning by looking for condensation on a cold shiny surface held just above the detector.

Second, measure the actual flow of hydrogen to the detector using an external flow meter- there might be a fault with the flow sensor. Varians came with a rubber bung to plug into the top of the detector when measuring flows. Turn off the air, make up and carrier.

If the flow really is very low, turn off the hydrogen generator and vent the line. Connect a pressure gauge to the line and turn the generator on. What pressure do you get ?

The strange thing is that an FID is usually harder to light than to keep burning once it is lit, so there could be something strange wrong with the GC. Does the indicated hydrogen flow to the detector ever change ?

Are you sure that the detector is hot ? - Varians will not allow hydrogen flow until the detector tower is above 150C.

Peter

[twranger]

I would verify the generator is functioning- we had an old hydrogen generator, and I was told the membrane that separates the water is shot once it is allowed to dry. Try a hydrogen tank if you can get one.