Thanks very much! Isotope Geochemistry came through!
1. With respect to this specific manufacturer, we know that multiple pumps
in their hands failed.
We opened up the flight tube and found several kinds of particulates that
did not originate from our use or the turbo explosion. I personally will
follow the course of asking the factory to disclose their cleaning
procedures. We are also doing SEM on the buggers.
2. More general observation: a few years ago, I found little magnetic
metal whiskers in disassembling an IRMS ion source. They were all over the
insides of the feed through wells in the flange area. They were very
difficult to remove.
We figured they came from the bolts used to fasten the conflat. Just goes
to show that the mass spec will know exactly when you are trying to be
cheap with things like plated bolts and such.
University of Toronto
On Thu, 15 Sep 2005 08:55:00 +0200, Torsten Vennemann
<[log in to unmask]> wrote:
>Dear Irene and others interested,
>we have had a turbo (not Leybold!) blow up on us too on our Delta-S. This
>was the turbo installed to allow us to do carrier gas analyses on that
>machine, that is it was/is installed just behind the hydrogen collectors.
>Not only did the oxide and/or metal dust cause a short on one of the
>hydrogen collectors, but we also had a lot of metal powder enter the
>tube.... We noticed this as our CO2 signal got really unstable, but this
>was only months after the turbo blow-up. After lloonngg hours of checking
>all other possibilities for this instability (source, capillaries,
>collectors, magnet stability...) it finally turned out that there were
>metal "stalagmites" within the flight tube. We actually first heard them
>when adjusting the magnet position (little creaking noise). To really see
>them required us to open up the flight tube completely (ion source, H2- as
>well as CO2-collectors removed to get access and sufficient light into the
>flight tube). I guess with several venting/pump-out stages, switching the
>magnet on and off etc., these metal stalagmites accumulated slowly but
>finally became big enough to divert the ion beam for CO2. Dry vacuum
>cleaning of the tube did the trick in the end...
>I sincerely hope you will not have this problem!
>Good luck and best regards,