FID Pops but doesnt seem to stay lit

[NiZmo]

Hey

Im using a Perkin Elmer Autosys GC, its been running for a while now but the air rescently ran out so we got a new one in, after 2 attempts as they kept sending O2
But since the new bottle it just doesnt seem to want to stay lit, it makes the pop but no vapour trails on glass.

Ive red the other recent FID problems page and ive checked the air flows manually using a flow meter and there the same as it was last time.
only thing i can think of is dodgy air but it seems to want to lite, and i jsut came accross this forum today and thought id ask for any help

thanks if you can
Ad

[Peter Apps]

Hi Ad

It is possible that the glass is warm (I know because I've done it !). Check whether the baseline has risen when you light the flame, whether turing the makeup gas on moves the baseline, and whether if you inject something you get a peak. If the answer is yes to these the flame is lit.

If the flame does not light, check the hydrogen flow. While igniting decrease the air flow to 1/2 or 1/3 of its normal flow, and have the make up gas turned off. Check also that the flame tip is properly seated and that there are no leaks at the column connection.

Are there other GCs using the same flame gasses ?, if so are they experiencing the same problems, if they are it points to a gas composition problem.

Peter

[phenol guy]

Check to see if you flame tip is partially clogged. This could be affecting its ability to stay lit. If you can light it with the air at 1/2 the full flow rate and it goes out as you open it further, the flame tip needs cleaning.

[yaoguocan]

i think you should check whether the carrier gas hydrogen gas air have been into the detector
2. check the setup of flow rate
3. check the working condition of relay for ignition
4. check wether the detector has been contaminated or clogged

[Russ]

I think someone else had this problem recently and they found that they had to clean their detector. We had a similar problem years ago and noticed a "wet" black residue on the FID collector and jet. After cleaning, the detector would stay lit.

[NiZmo]

Thanks for all the help, check all of them and it still didnt work, HOWEVER, we did find out what was wrong and its working now

we got the gas company to replace the air they sent and it didnt work, so we asked them to check the gas bottle to find out what its contents was for us...they came back and said they couldnt determine exactly its contents.

They then supplied us with another "99%" pure bottle and its working fine now

well almost fine, it now seems that im not getting peaks on my runs....yet another problem

[AICMM]

NiZmo,

Assuming your baseline rises when your FID is lit and you see moisture, the next thing I would do is a manual injection of some solvent like hexane or pentane or butane to eliminate the autosampler. Still no peak, make sure there is column flow at the detector end of the column. Still no peak, check the column position in the inlet and the flows.

Best regards.