Hello Torsten,

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.

Irene Ellis
IsoTrace Lab
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 
flight 
>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,
>
>Torsten.
z