We are having a very difficult time igniting our Hewlett Packard 5890 GC flame ionization detector. Most times, after we've let it sit idle for a few days, it will ignite without any trouble. But if we have to extinguish the flame and re-light it the same day, it simply will not ignite. We have tried to re-ignite it using the same gas pressures and we've varied the pressures from our standard to try and get it to light. The FID will pop, but will not ignite. Any suggestions? Thanks.
By Anonymous on Monday, March 18, 2002 - 01:37 pm:
Likely cause may be found in line below starting with "conclusion..." but if not, then:
Back to basics.
Disconnect column from detector.
Close off detector from oven.
Turn off all gases.
Turn on make-up and measure the flow. Set flow to specs.
Turn off make-up and turn on hydrogen. Measure and set hydrogen flow to specs.
Turn off hydrogen and turn on air. Measure and set air flow to specs.
Turn on igniter and check to see if glow plug is glowing. If not use flame to ignite FID.
Turn on all gases.
Try to ignite FID.
This should work unless your flame jet is not sealing properly.
By Anonymous on Monday, March 18, 2002 - 02:04 pm:
First, make sure that the ignitor glows when you hold the button down; if not, loosen then tighten the ignitor using a 5/16" wrench. If ignitor still doesn't glow, loosen then tighten the base screws, to establish good ground circuit. Third, replace ignitor. If ignitor DOES glow but has trouble lighting, we blow gently directly into the FID while holding the ignitor button down.
By Chaiyapon Ch on Tuesday, March 26, 2002 - 11:14 am:
Check connect nut 1/4" lowwer detector may have leak to oven and replace a graphite ferrul 1/4"
the other cause check the vent tube 1/16 of controller flow module.
By Anonymous on Wednesday, April 3, 2002 - 09:26 pm:
Have you cleaned the detector and jet? Turn the makeup flow off, decrease the air flow, and increase the H2 flow slightly. If the ignitor does not work try an external flame.
By Russ on Thursday, April 4, 2002 - 06:42 am:
Have you checked the air flow when the ignitor button is pressed? Even on the old non-EPC systems, the air flow should drop. I have some old notes indicating it should be around 100 mL / min with the ignitor pressed. This is assuming a "normal" air flow of 400.
By Anonymous on Friday, April 5, 2002 - 05:56 am:
Did any of these contributions help answer your question?
It is polite to acknowledge you received contributions from the forum and to state what was useful and what was not. At least we know from this you did read them.
But also it is to help others with similar problems and to show appreciation for the time and effort contributors took to answer your question.
Am I wrong?
By Jacob Reed on Monday, April 22, 2002 - 08:25 am:
Anonymous Friday April 5,
Nope, you're right. It is polite and helpful to respond to the contributions received over the forum and quite rude to allow one's busy schedule to take precedence over a kind response. I apologize to all of those who've I've offended. Our FID finally lit and honestly, I can't pin it's ignition on anything in particular. I tried the suggestions from "Anonymous" (Mon March 18) and from Chaiyapon Ch (Tue March 26) using standard pressures and variable pressures with no success. I also examined, cleaned, and reassembled almost every part of the machine having to do with the FID. Finally, I tried what had worked in the past: setting all the pressures back to the standard and leaving the GC alone for several days. Sure enough, one morning after having not tried to light the FID for almost a week, the FID ignited on the first try--same airflows and techniques as used days earlier. So, since then, we've been catching up on running samples. Again, I apologize for the VERY tardy response. Russ, I didn't get to check the airflow when the ignitor is pressed. I'll do that next time I'm in the lab. It may be a while as we're in planting season now and will be busy for a month or two. Thanks again for everyone's help. Any additional comments are always welcome.
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