Our lab too has been using Supelco's high capacity gas purifier system with great success for longer than I care to remember.

The systems have never let us down thought one has to be aware of the fact that the chemisorption process on which this purifier is based is temperature dependent. In other words, the power goes all the crap that was trapped on the cartridge is coming off.

So, we use our system in tandem with an OMI purifier tube (also from Supelco). These tube are self-indicating (turn from black to an interesting shade of brown). Since the LiH based they are exceedingly sensitive to water. The fact that even after one year there is hardly any colour change speaks (a) for the quality of the high capicity gas purifier system and (b) the quality of the cylinder helium we are getting delivered (CP grade; depending who one asks this is either 99.998 or 99.999%). However, we have used this set-up in conjunction with 99.995% helium as well with equally excellent results.

BTW, I never trust the claims made by our gas supplier on the label (certificate of analysis they call it) attached to the cylinders. I know of three instances when they supplied a forensic lab with CP grade coded cylinders they had mistakenly filled with balloon grade helium (grade A, 94-96%).  Even though the certificate of analysis never changes, we have noticed changes in Argon background from on cylinder to the next. While Ar is not a problem (as long as it's <100mV) and not scrubbed by the purifiers, seeing these variations is reason enough for me to stick with the purifier routine. I don't know who coined the phrase but my motto is "prepare for the worst and hope for the best".

The reason why I remember the 3 balloon grade helium incident so well has to do with the fact that, drum roll please, the 3rd bum cylinder was delivered free-of-charge as a gesture of goodwill to make up for the 2 previous bum cylinders. The words insult and injury spring readily to mind.


Best,

Wolfram

**************************** 
Prof W Meier-Augenstein, CChem, FRSC 

E-mail: [log in to unmask] 
JHI: http://www.hutton.ac.uk/staff/wolfram-meier-augenstein 
MIS: http://www.isotopesignatures.co.uk  


-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Shuangquan Zhang
Sent: 09 June 2011 01:05
To: [log in to unmask]
Subject: [ISOGEOCHEM] purifier for He supply for IRMS

I am looking for the information on the purifier to work best for the He supply line for an IRMS. Any information would be greatly appreciated.

Thanks,

Shuangquan Zhang
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