Thank you to everyone who responded. Here's a summary for those who are also
looking at He leak detectors.
Most of those responding are using thermal conductivity detector (TCD) based
devices. These are, typically, the less expensive style of leak detectors.
They all report sensitivities of 10^-5 cc/sec for He (a bit lower for other
gases). Most (all?) of these will detect any gas that's different from the
reference calibration. Some (all?) will display N2 differently from He
(for example). Some have a separate detector on the device itself for the
reference gas while the test/source comes from the inlet at the end of tube
placed near the potential leak; others have you calibrate the reference away
from the source and then have you bring the tip of the device close to the
potential leak/source.
Handheld, no tube:
Ion Science has 4 models
G1 = qualitative measurement, no logging or stored calibrations for
other gases (~$2.5k)
G2 = quantitative measurement, no logging, stored calibration for 1
gas (~$3.7k)
G3 = quantitative measurement, data logging, stored calibration for
many gases (didn't get a quote, but more expensive than G2)
Tesla = identical to the G3 but with shielding so it can be used near
magnets (the brochure is clearly aimed at the medical MRI crowd)
Matheson 8067 ~$3.7k (body style looks identical to the Ion Science
detector)
Box style with tube to get the inlet closer to the source:
AGC 21-72 (~$2.3k)
Gow-Mac 21-070 (~$1.4k)
Note: you can find the older Gow-Mac model (21-250) for ~$500 as
used/refurbished equipment.
Handheld with tube to get the inlet closer to the source:
GL Sciences LD230 (~$1.3k)
Restek 28500 (~1.2k)
Comments from people using TCD devives:
"I had a good experience using [Ion Science GasCheck Tesla] back when I
was in Ohio."
"We have 2 of the GL Science LC239. We used them when building the
recovery system and doing coldhead changes. They pick up different gases
but He and N2 register in different colors so it is very helpful."
"Try some of the chromatography suppliers. Restek makes one similar to
what you have been looking at for $1,135 which I use for my GC/MS
systems."
"I've had good success finding helium leaks in the seals of our
magnets using a Restek Electronic leak detector. The detector is
currently priced at $1,135"
"[Gow-Mac 21-070] is what we have been using for years. BUT, the list
price for what is apparently this model on the Millipore-Sigma web site
is $1920!! I am sure we paid less than $600, but that was a few years
back."
"When I was involved with the NMR operation at the CCRC at the
University of Georgia (I retired last year) we used to borrow an older
model Restek portable helium detector from Chemistry on occasion for
checking our recovery system. It worked well, so likely the current
Restek hand held helium detector, which appears to cost about $1.1K,
should be good as well."
"We use a Restek leak checker,
https://www.restek.com/en/products/accessories-labware/gc-accessories/gas-purification/8175/ -
in large part because we're just borrowing it from our mass spec facility,
and they already paid for it. I'd probably buy another if we needed a
dedicated unit for the helium system, though.
Advantages:
o Only $1100
o Exceedingly sensitive
Disadvantages:
o Downright excessively sensitive at times, can lead to false
indications of leaks that are actually just from localized air drafts, and
even leaks that are too small to matter for recovery can max out the scale
o Slow response time
o Qualitative measurement only"
A few people use the more expensive style of detectors; these
are basically small MS units on a cart - more expensive, but very high
quality. I have not looked into the details of what's available as
these are outside my budget, but some people might prefer these to the
simpler TCD devices.
Comments:
"we borrow a helium detector from Physics. It's on a large, on a cart, and
looks like it's from the 70s. Works great though! I suspect it's much more than $5k"
"I got a used Agilent PHD-4 ($9.5K). IT has been essential this last
week. I've been closing leaks with the help of my TA. It's more
expensive, but portable or my 8 floors of copper header and leaky QT
metal tanks. It is a bit of overkill. I'm not sorry I spent the money
though. The laser lab borrowed it to close their vacuum chamber last
week. It is creating contacts within the University, which is worth the
money for me."
There was also a very interesting anecdote about using a binary
gas analyzer that I think is important to share as more people find
themselves installing/running/troubleshooting a He recovery system:
"We have a Stanford binary gas analyzer for inline detection SRS BGA244
don't know what we would have done with out these 2 units when
setting up and trouble shooting the recovery system.
When we got our system hooked up we were having to change the LN2 trap
every 48L of liquid made which is not how that is supposed to work. So
we put the binary gas analyzer inline before the trap and found that our
gas had 16 to 20% impurities. So then we put it in before the bag and
after the bag to see if it was from the magnets or the bag it was
neither. So it had to be the compressor or the gas cylinders so we ran
some temporary tubing to be able to test those things and found that the
compressor had some major issues. We were confident it was not the tanks
and the plumbing because those hand held detectors had pretty much found
all the leaks and this would be a large one to get that much impurities.
Now the analyzer lives inline before the purification system so we can
see how things are going. We have pumps on the system and a DNP that
they bake out every couple of months so it is nice to be able to see how
that affects things.
Really think this analyzer or similar should be recommended by the
companies to have. It would be nice to know what places see coming off
the systems and after the bag etc. That way a company could say you are
good or oh you have issues we need to find out what is going on.
-Scott
---
Dr. Scott Burt
Teaching Professor
NMR Facility Manager
Department of Chemistry and Biochemistry
Brigham Young University
C414 BNSN / C008A BNSN
Provo, Utah 84602-5700
Phone: (801) 422-2404
chembio.byu.edu/nmr-facility <https://chembio.byu.edu/nmr-facility>
email: srburt_at_chem.byu.edu
Received on Thu Mar 31 2022 - 12:44:14 MST