I used to use swagelock fittings to secure Kel-F fingers until one did slip
off when warming up after being frozen down. The result was not
catastrophic but decidedly unpleasant. If you use swagelocks then a back up
clamp is essential.

An alternative (and safer) solution is to use a VCO face seal fitting,
fitted with a hard PTFE or a Kalrez O-ring. A retaining flange is machined
onto the top face of the Kel-F tube so that the finger is at all times
captive in the fitting and cannot slip off. Vacuum performance is fine.


Dave Mattey

Geology Dept, Royal Holloway College, University of London, Egham Hill,
Egham, Surrey, TW20 0EX

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