Hello all,
I was asked to post this on behalf of Pavel Kostikin from Bruker.
Ben Ramirez
##############################
In a recent post, the need to use He 6.0 to operate Bruker’s
CryoProbe System has been questioned.
The required purity of the He gas has always been specified by Bruker
to be
He 6.0 (99.9999%, total contamination level <1 ppm). This is needed to
ensure
proper long-term functioning of the CryoProbe System. The customer is
responsible for making sure that this requirement is met. Using
inferior quality
He gas may lead to severe contamination of the CryoSystem, requiring
frequent
warmups and a potentially costly decontamination service visit.
Individually certified He gas cylinders offer the advantage over batch-
certified
He gas cylinders in that the quality of the gas in a given cylinder is
certainly
fulfilling the specification. With batch-certified He 6.0 gas, it is
only certified
that the gas fulfilled the 6.0 specification before filling it into
the cylinder.
Therefore, individually certified He gas cylinders are recommended.
However, Bruker does not favor any specific gas supplier.
Also, Bruker does not have any commercial interest in any gas supplier.
Pavel Kostikin
National CryoProbe Product Manager
Bruker BioSpin
> From: Robert Peterson <peterson_at_mbi.ucla.edu>
> Date: October 7, 2011 6:36:44 PM CDT
> To: AMMRL <ammrl_at_ammrl.org>
> Subject: [Fwd: AMMRL: grade 6 helium for cryoprobes]
>
> Hi everybody,
>
> Thanks for the prompt and numerous replies! The consensus seems to
> be that normal grade 6
> helium is good enough. Only one respondent thought that MR grade was
> necessary, and many
> hadn't tried it or even heard about it.
>
> Astonishingly (to me), two people said they used grade 5! I was led
> to believe that attaching
> grade five to the cryoplatform would cause it to change lanes
> without signalling, fishtail, crash
> into the magnet, and ignite, taking my whole lab with it. (The
> details might not be exactly
> right, but it was something like that.)
>
> Just to answer one of the respondents and give a little more detail
> about the MR grade helium:
> Walter Osgood at Bruker told me that he convinced Praxair to make
> this product. So as far as
> I understand, it was designed specifically for use with cryoprobes.
> Walter tells me that if you
> put grade 6 helium into a normal cylinder, the helium gets
> contaminated by outgassing from
> the walls of the cylinder, and often you're left with something
> closer to grade 5 helium. The
> reason the MR grade is supposedly better is that they use better
> tanks, and they bake the tanks
> to remove impurities that might outgas into the helium. And then the
> gas is tested after it's put
> into the cylinder to verify that it's still grade 6.
>
> However, from my own experience and your comments I'm less and less
> convinced that it's
> really necessary. I'm going to think about it some more, but I may
> go back to using normal
> grade 6.
>
> Thanks again!
>
> -Robert
>
> ****************************************************************
>
> Robert, We were using the regular "six nines" all the time at Kansas
> on
> two cryoprobes, and never had any problems with it. At the time I
> think
> that was costing us about $300 a tank.
>
> ****************************************************************
> I've been using "UHP" helium for our cold probes. It is marked 5.0
> when there is a number on it. ca. $230 for a normal-sized cylinder.
> I've never had an issue. Our 500 MHz cold probe has been running for
> almost 3 years (periodic warmups and cool downs for various reasons,
> but I've only had the RT probe in for a few months during that time)
> since the last time it was serviced and I don't have any degradation
> of performance. So my opinion would be that even at $700 per
> cylinder you've been spending much more than you need to. Up to now
> our helium has come from MEGS (not sure what their QC is on it), but
> the university contract with them has run out, and in future I'll be
> getting it from Praxair- I'm assuming I'll have similar grade and
> similar price from them.
>
> ****************************************************************
>
> At my old institution, we ran our Varian cold probe with 5-nines He
> just fine (per Varian's recommendation), and today we run our Bruker
> cryoprobe with 6-nines. We've never used individually-tested
> cylinders.
>
> One difference between vendors is that our Varian cold probe
> occasionally needed "conditioning" if it was idle for a day or so.
> According to them, material builds up on the coil, so you run a
> procedure with a lot of high-power pulsing for a half hour or hour
> to volatilize that stuff. We've never done anything like that on our
> Bruker probe, and I have to wonder whether it has something to do
> with the grade of helium.
>
> Regular 6-nines should still be good enough, though.
>
>
> ****************************************************************
>
> Seems like a scam to me, but Bruker
> sure seems to think it's necessary.
> FYI, I have only used 6 9's He with
> our cryosystem (at Bruker's insistence). I'd love to hear the
> responses you get on this topic.
>
> ****************************************************************
> Our local Praxair sells us HE 6.0RS-T for $317/cylinder. I do not
> have any long-term experience with this yet, but the Bruker
> installation engineers had no problems with it when we supplied it
> for them.
>
> ****************************************************************
>
> Every gas supplier should be able to provide 6.0 helium, so if you
> can check with other suppliers besides Praxair, it might be worth
> it. Our 6-9's helium has a bulk certificate, and have had no
> problems. We have used Linde and Airgas in the past... most of the
> problem is delivery time, so we always have a 'spare tank' on hand,
> and order from the chepest supplier with certified gas.
> That is very pricy gas!
>
> ****************************************************************
>
> The amount of contamination specified for each of the Grade 6 gases
> is the same, so we use the cheaper "Electronics Grade" 6. As you
> say, each batch is tested. If you believe that all cylinders from
> one batch came out of the same tank, and you believe in the laws of
> Physics, then that should be good enough.
>
> The MR grade is only for when absolute certification is required
> under strict ISO quality control standards. If you don't have an
> ISO standard that requires MR grade, you're wasting your money using
> it, IMO.
>
> ****************************************************************
>
> Actually, I understand your concern, but from our point of view it
> is worth having the certificate. Bruker thinks so too. One
> contaminated cryoprobe system can cost easily $30K to repair and
> Bruker has had to deal with this at several places. Given that each
> of these cryoprobe helium cylinders typically last at least 1 year,
> it seems a small price to pay.
>
> ****************************************************************
>
> We have been usung Grade regular 6 for years with no issues.
> Presently running 9 cryo platforms.
>
> ****************************************************************
> I've also used both individually-tested cylinders as well as batch-
> tested cylinders, and never had an issue with it either way. Either
> the "research grade" helium, whose O2 and N2 impurities are supposed
> to be less than 0.1 ppm, or the "chromatographic grade" helium,
> whose O2 and N2 impurities are supposed to be less than 0.5 ppm
> (total impurity not to exceed 1.0 ppm), worked just fine for our
> cryoprobe, on our 600 MHz system. While I'd certainly be happier
> having only research grade helium (individually tested tanks), I
> wouldn't be uncomfortable at all using the batch-tested
> chromatographic grades of helium, since both are still 99.9999%
> pure. If I recall correctly, there was some fellow even using VLSI
> grade (also 99.9999) helium supplied by Scott Specialty Gases, which
> had a guarantee of less than 1.0 ppm for each N2 and O2, which is
> twice the accepted contamination of the chromatographic grade helium
> that I've used a few times. I've also encountered a couple of folks
> who didn't do a good enough job of purging the system when switching
> out tanks, and despite the contamination, were still doing just
> fine. I suspect it's not a mistake that they'd want to repeat,
> though.
> ****************************************************************
>
> Just a data point for you - I've been using regular grade 6 helium
> with our
> cryoprobes since installation in early 2007, and haven't had any
> problems.
> Perhaps more telling, Bruker seems fine with that.
>
> ****************************************************************
> ****************************************************************
> ****************************************************************
> ****************************************************************
> ****************************************************************
>
>
>
> -------- Original Message --------
> Subject: AMMRL: grade 6 helium for cryoprobes
> Date: Thu, 06 Oct 2011 16:59:24 -0700
> From: Robert Peterson <peterson_at_mbi.ucla.edu>
> To: ammrl_at_ammrl.org
>
>
>
> Hi everybody,
>
> I'm looking for information about "MR grade" helium from Praxair
> (part# HE6.0MR-T). The difference between normal grade 6 and MR
> grade 6 helium is that normal grade 6 helium is batch-tested and
> then put into the cylinders, while each cylinder of MR grade is
> tested for purity after it's put into the cylinders. Each cylinder
> comes with a certificate showing that the helium coming out of THAT
> cylinder really is grade 6.
>
> I've mostly used MR grade for the last few years, but I've
> occasionally gotten a normal grade 6 cylinder and used it. I've
> never noticed any difference in the performance of the cryoprobe (or
> any purity issues like the preamp heater power dropping quicker). I
> just called them to order a cylinder and discovered that they've
> approximately doubled the price. They're now charging $1429.09 for
> one cylinder. At that price I'm wondering if it's really worth it.
>
> Does anyone have any strong opinions about this?
>
> thanks,
>
> -Robert
>
> --
> -----------------------------------------------
> Robert Peterson, Ph.D.
> Facility Manager - NMR Technology Center
> UCLA-DOE Institute for Genomics and Proteomics
> UCLA Dept. of Chemistry and Biochemistry
> phone: (310)825-1816
> fax: (310)825-0982
> peterson_at_mbi.ucla.edu
> -----------------------------------------------
Received on Thu Oct 13 2011 - 09:22:16 MST