Chromatography Forum

G'day everyone,

Ive done a little searching within this wonderful forum and came across 1-2 older posts on this subject, like back in 2014 so thought i would raise this topic again for current advice.

I'd appreciate any feedback users have of any brand or model of electronic leak detectors for GC carrier gas namely He and N2, and what people have preferred the most if they have used multiple brands in their work life.

Specifically, our lab is looking at the Restek REST-28500 unit, (which is the replacement for REST-22655) to replace a very trusty but now dead Alltech unit

any experience with this unit perhaps?

muchas gracias for any feedback and advice
Greg

... for GC carrier gas namely He and N2, and what people have preferred the most if they have used multiple brands in their work life.

Specifically, our lab is looking at the Restek REST-28500 unit,
Greg

You shouldn't be disappointed with Restek 28500 however due to the principle of operation minimum leak detection of N2 is 100x worse than for helium or hydrogen. IMHO 1.4 µL/sec minimum detectable N2 leak is not sufficient for carrier gas.

Back when I was working, we had a Restek unit that worked fine.

Been using the Restek one for a long time now and it just keeps working. Had to send it off and get the battery replaced once but otherwise never a problem.

N2 is less sensitive, but not sure it is much less sensitive than using soapy water or Windex, and without the cleanup/contamination problems.

...
N2 is less sensitive, but not sure it is much less sensitive than using soapy water or Windex, and without the cleanup/contamination problems.

Sensitivity of leak detector is 1.4 µL/s this roughly equals bubbles of diameter 1.4 mm every second. I bet you would see smaller bubbles (at least twice) what makes bubble method more sensitive. One can use IPA instead of soapy water to avoid contamination problems.
I had to replace the battery as well. In fact it was my fault because once it has discharged below a certain voltage what caused charging was not possible anymore (due to battery management system). However one can charge such battery outside leak detector ommiting BMS and it will work normally again.

Thank you dblux_, James and CPG for your feedback and comments.

I note the poor sensitivity of N2 is similar for different vendor leak detectors. Would this be due to the principle by which these detectors work based on thermal conductivity and nitrogen of course is very close (if not the same) as that of 'air' which is 80% N2 anyway?

Again, thank you for replying, much appreciated

Greg

...
I note the poor sensitivity of N2 is similar for different vendor leak detectors. Would this be due to the principle by which these detectors work based on thermal conductivity and nitrogen of course is very close (if not the same) as that of 'air' which is 80% N2 anyway?
...
Greg

Yes, that's the reason.

Thanks again to those taking the time to reply.

We've gone with the Restek leak detector unit and a flow meter too.

As others have mentioned, the Restek one is a solid unit. We've been using ours for 10+ years. Very happy with it. The only thing I don't like is it cannot be used while charging. So keep it charged at all times

I'm using the REST-22655 and its great for H2, He, Ar but not so much for N2. I ran my battery down right away and had to send it back because it would not recharge. This was in the first months of having it. They scolded me for getting it dirty on the inside of the detector 'a very expensive cleaning' but did it for free because it should have recharged. As for getting it dirty. Just checking line fittings and inlets. We only have 4 GC's so it was hardly overworked. This unit has saved a lot of gas. We just about doubled the lifetime for our cylinder usage.