6890 FID Air Flow won't Turn Off

[AZBiodiesel]

FID Air flow will not reduce to setpoint. Front FID will light, but the rear FID blows out the flame as soon as the air flowrate increases. With all flows off, the Air flow on rear FID is 120 mL/min. On front inlet it is stuck at 22 mL/min. I have confirmed these flows with a flowmeter. Air flow will drop to 0 if air is blocked with external valve in the line.

Air line pressure is 80-100psi. I brokedown the FID and inspected it, very clean, jet is not plugged, and column installed properly. Column flows are as they should be through the FID.

So, is there an internal FID flow controller or valve that could be stuck open or allowing air to get by & can I fix it or will I have to order the new part?

Thanks,

[dblux_]

...So, is there an internal FID flow controller or valve that could be stuck open or allowing air to get by & can I fix it or will I have to order the new part?

Thanks,

It's called EPC. Not cheap at all.

[AZBiodiesel]

Correct. About $3,000, as just quoted to me from agilent. I took off the lines in the back, it looks like the fritted filter disc has gotten pushed into the unit probably by particulate buildup or moisture. I am also looking at taking out the module, unscrewing the air inlet port and trying to fish out the disc (wishful thinking)...

Anyone attempted to change out this disc before?

Thanks,

[Yama001]

I have tried several times to clean EPC inlet modules - always failed. Perhaps the detector line version is simpler.

I have seen these folks mentioned as a repair alternative on these boards:
http://wntechnical.com/6890epcrepair. I have never dealt with them, though.

[AZBiodiesel]

Thank you for the link Yama.

[skunked_once]

I have seen these folks mentioned as a repair alternative on these boards:
http://wntechnical.com/6890epcrepair. I have never dealt with them, though.

I can vouch for them as I have used their services often and have always been satisfied.