Model 51i Total Hydrocarbon Analyzer

The FID flame is lit by applying a controlled voltage to an igniter that screws into the side of the detector housing. The igniter contains a small coil of wire that produces a red-hot ignition source when electric current flows through it. Over time, the igniter can fail due to normal wear or due to exposure to corrosive atmospheres. The Model 51i comes with a spare igniter already installed, which would just need to be plugged into the connector in place of the failed igniter. See the Thermo Scientific Model 51i User Manual for installation instructions.

If the analyzer is running in an open rack or an area with normal ventilation, the FID exhaust can be left open and does not need to be vented. This is the preferred configuration. However, if the analyzer must be mounted in a small enclosure without ventilation, the FID exhaust port should be connected to a vent line that runs to an exhaust system. The reason for this is so hydrogen does not accumulate and create an explosion hazard in the event of a failure. 

The Model 51i is offered with two fuel-type options: 100% hydrogen or mixed fuel (40% Hydrogen, 60% Helium). Hydrogen is used for applications with 20.9% oxygen content. Mixed fuel is used for low-oxygen–content applications or applications with varying oxygen content. For most CEMS applications, mixed fuel is the best choice. Sample Streams from CEMS (especially combustion sources) usually have varying oxygen content. Refer to the Thermo Scientific Model 51i data sheet for detailed configurations available.

Here are some quick tips for remedying a flame-out issue:

1. Is the unit running with the proper fuel type?
   
2. Is the FID exhaust tubing causing a restriction?
   
3. Is the igniter circuit working? Check to see if the flame temperature increases during an ignition sequence.
4. Try swapping to the spare igniter.
   
5. Do the current ignition and run pressures match the silver sticker on the oven cover?

If you are unable to get the unit to light, contact our Technical Support Department at (866) 282-0430, option 2.

Refer to these resources when creating a spare-parts strategy:
Model 51-HT parts kit
Model 51i-LT parts kit
If you have a different gas analyzer, visit our spare parts kit information page. To order parts call Customer Service at (866) 282-0430, option 1.

Look for next month's Fast5 in your inbox on Tuesday,  February 2, 2016 or visit Fast 5 Issues