>
>         In general, what type of ferrule is recommended with metal-to-metal
> swagelok connections--teflon or steel?
>
> ********************************
> Steve Nelson
>

Steve,

It all depends on what your needs are. In general, I would highly
recommend steel-to-steel connections, SS tubing and SS swagelok front
and back ferrules. If either is softer/harder than the other the
ferrule will cut its way through the tubing (e.g. SS ferrules on Cu
tubing) too much or not at all (e.g. brass ferrules on SS tubing).
Either way will eventually end up with leaking connections.

However, I found that Teflon can be used on SS tubing quite
successfully. Yet, despite these good experiences I try to restrict
their use to gas supply lines rather than high vacuum lines.

Having said that, the approach suggested by Joe Cali sounds very
good to me. I will certainly try to adopt his idea (SS back, teflon
front ferrule) for my SS vacuum line. Not because I am concerned
about corrosion but this combination might effect an even better leak
tightness.


All the best,
                          Wolfram



*****************************************************
Dr. W. Meier-Augenstein
Lecturer/Research Fellow

University of Dundee, Dept. of Anatomy & Physiology,
Small's Wynd, DUNDEE  DD1 4HN, United Kingdom

Tel.: +44-(0)1382-34/5124, /4968
      +44-(0)468 -314563
Fax:  +44-(0)1382-34/5514

e-mail: [log in to unmask]

URL: http://www.dundee.ac.uk/AnatPhys/wolfram.htm
*****************************************************