How do you know when the liquid nitrogen is low (DT-GCMS)

Discussions about GC and other "gas phase" separation techniques.

3 posts Page 1 of 1
I have a GL Sciences Optic 4 inlet and cryotrap. It runs on ~35 psi liquid nitrogen, but there's some level of liquid which is not enough to cool the trap to -140. The tank pressure gauge will read 35-40 psi, and the liquid level gauges rarely work.

Do you have a method or tip for knowing when you're about to have too little to run your trap?

I've consider a continuous read scale but am hoping there are simpler or better options.
On my 200 liter Dewars I use the rock and shake method to check the fill level. On my outdoor 2000 liter tank the gauge works.
Steve Reimer wrote:
On my 200 liter Dewars I use the rock and shake method to check the fill level. On my outdoor 2000 liter tank the gauge works.


The gauge was always terrible on ours too, so I would rock it and tilt it at about 15-20 degrees and if it still had liquid you could feel it sloshing back and forth, after a while you can learn about how much is left in them. If it doesn't slosh then you know it is pretty much only gas left.

If the humidity is high, you can also judge by the frost line at the bottom of the dewar, though there really shouldn't be one if it is insulated properly.
The past is there to guide us into the future, not to dwell in.
3 posts Page 1 of 1

Who is online

In total there are 2 users online :: 1 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm

Users browsing this forum: Google [Bot] and 1 guest

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry