Can you see the flame in an FID

[leyrempillo]

Hi,

I have a CP-3800 GC with an FID detector. The system has not been used for a long time and I just set it up with an SPT.
I've checked the flows to the FID and the flows are correct. The FID is set to a temperature of 300C and when I ignite it, I can see the filament light up, but I do not see a flame. Also, when I turn on the FID electronics and ignite the FID I see the signal go up to around > 100 mV then slowly go down to around 5 mV. My question is, is the flame in the FID visible? I cannot see a flame but the GC does not give me a flame-out error message. I also tried what people suggested and put a mirror on top of the FID to see if the mirror surface clouds up and it doesn't. I am not sure if the flame on my FID is actually on.

[chromatographer1]

If the flows are set properly the flame will be invisible.

The best way to determine if the flame is lit is to place a cold piece of metal above the flame and watch the water vapor from the flame condense (fog) on the smooth metal.

A spatula or wrench is a good choice for this.

best wishes,

Rod

[cleh]

A small mirror works, too.

[dblux_]

Hi,

... My question is, is the flame in the FID visible? ...

It is visible, provided:

- you observe the jet tip directly
- room is completely or almost completely darkened
- your eyes are accomodated to darkness sufficiently long
- your eyes have normal sensitivity to blue color (that is no problem, since we all are sensitive to that light wavelength)

This is only formal answer for your question and has nothing to do with practical recognition of lit FID.
As posters wrote, best way is to utilize water vapour condensation on shiny, cold surfaces or observe FID signal on PC monitor.

[chromatographer1]

Be aware that UV radiation is being emitted by the flame and your retinas can be damaged by looking at the flame.

Oh the joys of science.

best wishes,

Rod

[dblux_]

Be aware that UV radiation is being emitted by the flame and your retinas can be damaged by looking at the flame.
...

It's an interesting aspect of safety connected with our activity.

Atom absorption spectometers are equipped with optical filters protecting operator's eyes from radiation of the flame (quite large). There are also precautions in manuals and labels to avoid looking on flame and into HCL radiation.

But there is no safety precaution (except for the danger of burning with hot surfaces) in the area of FID chimney of my 6890 althou one may easily look at jet tip with lit hydrogene flame.

I suppose Agilent neglected such precaution bearing in mind very limited UV intensity of this particular flame of really very small spatial area.

However thank you Rod for focusing our attention on safety aspects connected with our work.

[chromatographer1]

It was my impression that no one would spend hours staring into the flame, but one never knows.

GC is so addictive and it is so much fun to toast marshmellows during the boring analyses a safety precaution seemed the only correct procedure.

best wishes,

Rod

[uzman]

If the flame of FID is creating enough UV radition , you will die when you are cooking something at home.
May be the more important point when looking at FID flame , it may make small explosions if partialy blocked , and this may throw small particles into your eyes.

[chromatographer1]

Do you cook with a hydrogen flame at home?

SERIOUSLY, when using a hydrogen blowtorch to close capillary columns it was required to wear UV googles.

hydrogen when burning gives very little visible light, but with invisible UV light it is quite bright and can be dangerous.

best wishes,

Rod