FID flame cannot ignite

What temp are you trying to ignite at? What ratio of gas are you using?

Temperature:300.0

H2 flow:40.00

Air flow:400.00

Mode:constant makeup

Makeup (He) :25.00

Front inlet S/L

Mode:split

Temperature:250.00

Pressure:7.019

Split ratio:5.0

Split flow:23.50

Total flow:31.09

Septum purge:3.0

Hi pusakcute85,

I have updated the tags for better visibility . From the parameters above it should light and stay lit. You makeup gas is a little high and you may gain stability by lowering it to something like 10ml/min. The jet maybe partially restricted and this is hard to tell so I usually just suggest a jet change as a first pass. What model of GC do you have?

Regards

James

Hello all,

The ignitor could also be bad. When you try to ignite the FID flame, the ignitor should visibly glow. PN for this is: 19231-60680

Hi

1. Check flows that they are correct

2. Check/replace ignitor itself (sometimes there are deposits/rust or ignition coil have deformed and moved too much in)

3. Check that jet tip is really clean, replace jet with new one or use piano wire to open orifice (look with magnifying glass to see it well)

Hope this solves the problem

Agree with jarmo and will add the following tip:

Carbon from the ferrules can shave off when the bolt is tightened (FID inlet), causing the jet to block partially or the path/tube between the column and jet to partially block.

When the instrument is turned on (gas flow on) those carbon pieces from the ferrule or old dirt, blow into the jet (or just before the jet) and block the flow. Less likely is that the column is not properly cut so when the flow and heat are on, chips brake off the column end and block the flow. If the column is inserted carelessly the same can happen.

My recommendation:

• Use a flashlight to shine from inside the oven through the jet, then try without the jet (column and detector disconnected in both steps).
• Make sure that there is no visible dirt inside on the walls of the FID inlet (tube).
• Clean with wire (cleaning wire from Agilent or a thin .010 clean guitar string) and blow out gently with compressed air. See if the light intensity changes. It should get brighter if dirt was removed.
• Compare the light intensity with a new jet. It should now be brighter if dirt was removed.

This should identify if there is dirt, ferrule or column residue in the FID inlet that causing the problem.

If no dirt is spotted/no light intensity improvement with the flashlight - check column cutting technique and quality.

Hope this can help you in identifying the cause, regards, Pétur

L