6890 GC flow issues FID/TCD

Hi eme091,

When trying to measure smaller flows with a flow meter there can be some difficulty. The volume of the meter tubing(should be small),adapter to the detector (tight and proper fit) etc can play a factor. Also I have had a meter that had trouble with low flows and it was only resolved by making sure the meter had the gas type set correctly and was attached to the detector output and left alone (not moved)  for 10 minutes to stabilize . There are also some meters out there that are not spec to read low flows. What meter are you using?

regards

James

I updated the tags on this post so it will have more visibility in the community and others can comment.

It is an agilent brand flow meter, will check the model when I get back to work but it had no problem on another instrument a week or 2 ago and one of the detector readings done was at a similar flow.  I'm starting to wonder if it's the EPC board?

flow meter is Agilent ADM2000 universal gas flowmeter, was just calibrated 31JUL17

Yea also some tailing has been a problem.  May have to try changing out the EPC board.

Thanks

I wouldn’t jump to that conclusion necessarily. It certainly could be defective, but we normally suggest less intrusive tests and maintenance first. Have you run the inlet leak and pressure tests? Have you tried a different column?

Inlet leak/pressure test passes, and I have already changed out the column, same result.    Not sure where else to go would the EPC board or the module be more likely to malfunction?  instrument is 10 yrs ish old run 24/7 do either of these parts have a doc. life span?  Any other tests anyone can think off.

One thought does occur to me. If you are measuring the flow at a low oven temp, with low inlet total flow and low head pressure, the flow meter may add enough restriction that flow can divert flow out of the split vent. I have seen this when measuring flow with the oven off. If this is the case, try an oven temp of at least 80 C. We look forward to an update either way.

James

I switched the 2 EPC modules, same resulting low flow.  I think I am going to order a new board and see if that works.  Will post back result.  Thanks for the help.

Whats the total flow set at on the inlet? Are you doing this in split or splitless ? Make sure you are in split mode with at least 20ml of total flow.

Whats the total flow set at on the inlet? Are you doing this in split or splitless ? Make sure you are in split mode with at least 20ml of total flow.