Hi Matthias,
Standard grade helium is fine. The helium gas goes into the delivery dewar rather than into your magnet. If you are going to start worrying about what goes into the delivery dewar then you also need to worry about what everyone else uses (over which you have no control). I have been using standard grade helium fro > 25 years with no problems (yet!)
Regards,
Alan
Alan Kenwright
Reader in Spectroscopy & NMR Service Manager
Durham University Chemistry Department
On 2 Oct 2014, at 10:29, Matthias Findeisen <matthias.findeisen_at_uni-leipzig.de> wrote:
>
> Dear all,
>
> which Helium-Gas Cylinder do you use for refilling the magnet (i.e. to give slight pressure onto the refill dewar)?
>
> Is the specification of 99.996 % sufficient for this?
>
> Which experiences do you have?
>
> Thanks!
>
> Yours
> Matthias Findeisen
>
> Univ- Leipzig/ Germany
>
Received on Thu Oct 02 2014 - 21:30:39 MST