FidIG Troubleshooting
Most of the issues with the detector are probably not going to be related to the FIDIG. However, to be thorough, there is an extensive troubleshooting section below.
Symptom: The detector will not light. In addition, you should hear at least one and more commonly two pops from the detector as the gas flows ramp up. It is usually after the second pop that the detector will have a non-zero output.
- Flows: Check to make sure that the flows are up where they should be. Typical air flows should be at least 10 times the set point of the hydrogen flow. In addition, make sure the flows are ramping up to their set points. Make sure the gases are on. If using hydrogen as a carrier or adding additional hydrogen through a methanizer, make sure the total flows meet the 10:1 requirement.
- Flows: If you are pushing very high flow rates, make sure that you are using an appropriate sized jet for those flows. For example, a packed application at high flow rates should be using a 0.018 jet rather than a 0.011 jet to set the gas velocity at the right level.
- Glow plug: Check to make sure the glow plug is glowing. Try swapping with a glow plug from another instrument that is working. While lighting, you should visibly see color from the glow plug and, typically, you will see the glow plug get brighter as the air flow ramps up.
- Jet: Make sure the jet is not partially or fully plugged. Typically a partially plugged jet may light and stay lit for a bit but once an upset such as a valve switch occurs or a solvent front has passed the detector will go out. A fully plugged jet will not light.
- Leak: Look for a leak at the base of the detector where the column is connected to the detector. Tighten or replace detector base fittings, replace the column ferrules or reinstall the column if has become disconnected.
Symptom: Very high signal
- This usually happens when the signal spring gets knocked out of position and becomes grounded. Cool the detector and turn off the gas flow. Loosen the three long Torx screws at the base of the chimney and remove them. Disconnect the glow plug wire. Pull straight up on the chimney until it is clear of the detector. Replace the chimney assembly in one swift, decisive motion. This should push the signal spring back onto the collector.
- Look at the signal for the detector. It should be very low or zero. If not, replace the electrometer or signal bar. If it is zero, re-tighten the Torx screws, re-connect the glow plug and turn the heat back on to the detector. Re-light the detector.
Symptom: Very high signal
- Occasionally, this problem can occur when the detector has gotten wet. In this scenario, it is best to turn off the gas flows, turn the detector temperature over 200 C and let the detector bake for about an hour. Then re-try ignition.
Symptom: Detector keeps re-lighting
- This is often a result of the Lit Offset being set too high for the quality of the gases being used. If you can light the detector, even momentarily, look at the signal the detector is generating. Then go to configuration for the detector and ensure that this number is less than the current detector signal. By default this number is typically 2, on very clean systems a Lit Offset of 0.8 is not too low. If your FID is operating below the Lit Offset, adjust the lit offset to below your detector value. Try re-lighting the detector and see if it stays lit.
Symptom: No signal.
- Verify that the detector is lit: The easiest way to do this is to hold a glass vial over the flame and look for steam on the glass. If it is not lit, refer to the notes above. If it is lit but still no signal: check to see if the proper signal is assigned. Look at Analog Out 1 or 2 and make sure it points to the detector that is being used and not something like Test Plot.
If you have exhausted the list above and the detector will still not light, please feel free to reach out to us and we will happily work with you to troubleshoot what other issues may be causing non-ignition.