Speaking of leak detectors/seekers

[Roxanne42]

Any particular model to recommend...? Preferably not overtly expensive.

Mostly interested in detecting He, N2, H2 and CO2, CH4 - not sure if there is a model that does all five - found combinations of these though. I think N2's thermal conductivity is too similar to air's as well. I'm also looking into buying a leak detector for combustibles (H2, CH4) and CO (a much more common combination in industry) so really, the second one would only need to detect He/CO2 and possibly N2...

Do you usually check for air leaks (FID) with only soap solution?


Thanks,

Roxanne.

[Radish]

Roxanne,

I can't answer your question about leak detector devices, but I don't think you're supposed to use soap solution anywhere on a GC system.

[Rick]

Hi!
I use Gow-Mac leak detector model 21-250 since many year with no problem.
It is very sensitive...for N2 and O2 too.
For air....this is a problem...when i suspect a air leak, i replace air by helium and check for leak...never use soap in GC.

[randytoad]

I use a Matheson 8066 Leak Hunter plus. It has settings for He, H2, Ne, Xe, a bunch of CFC's, CO2 and Methane. I have only used it for He and H2 but have been quite satisfied. It's battery powered and portable about the size of a large calculator with a connected wand. It comes with an extension to the wand and an AC adaptor. Batteries (9V alkaline) seem to last quite a while. The one problem I have with it is that once it detects a large leak, it takes a while for it to clear. I believe they run a couple $K, but you might be able to find a used one.

[Bruce Hamilton]

I used the Gow Mac / Matheson thermal conductivity leak detector for about 20 years, with no problems. Its convenient, and generally I used hydrogen or helium carrier, so it's also sensitive. Costs about US$2000, and is still around.

I also used soap solution to check for leaks on other gases, such as nitrogen. I always ensure the systems were at positive pressure, and started at the pressure source and worked downstream. I washed the soap off with distilled water, and never managed to identify a problem caused by using it, and it is really quick way of finding major leaks.
Never use an electronic leak detector after using soap, you must ensure all liquid has gone, as the liquid will kill detector filaments.

However, if your instrument manufacturer prohibits it, the warranty is important, so maybe you shouldn't use it.

Bruce Hamilton

[Roxanne42]

I checked up the specs for the suggested Matheson 8066 and GOW-MAC model. Am I correct in thinking that the GOW-MAC will also detect helium, carbon dioxide, hydrogen and methane leaks? Do you happen to know if it's pretty sensitive for all four of these? It does not need any calibration does it? I know the Matheson requires yearly calibrations at a fee.


Thanks,

Roxanne.

[randytoad]

I checked up the specs for the suggested Matheson 8066 and GOW-MAC model. Am I correct in thinking that the GOW-MAC will also detect helium, carbon dioxide, hydrogen and methane leaks? Do you happen to know if it's pretty sensitive for all four of these? It does not need any calibration does it? I know the Matheson requires yearly calibrations at a fee.

As I said, I have never used my Matheson for anything other than Helium or Hydrogen, so I can't comment on how sensitive it is to the other stuff. It is VERY sensitive to He and Hydrogen. I also can't comment on the calibrations. I simply use it as a "go/no go" leak detector and am not interested in actually measuring the leaks, only whether or not I have one. I just test it with a known low flow source. If it beeps, it's working OK as far as I'm concerned.

[Bruce Hamilton]

Assuming it's the same Gow Mac as I used, it's got a thermal conductivity detector, and it compares against air sucked in the reference port on the front panel, and the sample from the probe.

Because H2 and He have very different thermal conductivities to air, it is very sensitive to those gases, and will be less so to CO2 and CH4.
Air 2.41, H2 16.84, He 14.15, CH4 3.02, N2 2.43, O2 2.44, CO 2.32, Ar 1.62, CO2 1.45, Water ( don't try ) 1.58. ( units k x10^4, at 0C )

As the reference port is accessible, you could feed in He to the reference, and have improved sensitivity for the other gases.

I used to test on the septum purge flow, and a quick pass across the GC port at 2 ml/min caused immedate full scale deflection and audio scream for bothe He and H2.

Please keep having fun,

Bruce Hamilton

[gcguy]

I use the Hewlett Packard one (part no 5182-9648). It tests for He,H2,Ne,Xe,CO2,Ar and CH4.

GCguy