Hi John,

It sounds like a very intriguing material! I wonder how suitable it would be
for piston rings, and rams for small steam pumps?

I’ll have to check to see if it is available commercially here in the U.S.

Thank you for the very clear explanation!

Keith



_____

From: halfinchlivesteamforum@...
[mailto:halfinchlivesteamforum@...] On Behalf Of John Baguley
Sent: Wednesday, May 02, 2007 8:50 PM
To: halfinchlivesteamforum@...
Subject: Re: [Half inch live steam forum] Helen Longish



Hi Keith,

The material I've used is a bearing grade thermoplastic containing 10%
Carbon Fibre, PTFE, and Graphite, which goes under various names such
as Ketron HPV and PEEK bearing grade. It's a lot harder than ordinary
PTFE and also has a lower expansion rate, although still much higher
than bronze or stainless steel. It will withstand a continuous working
temperature of 250°C, has a very low coefficient of friction and good
machinability.

I am not sure I would go down this route again as the fitting of the
valves is very fiddly and time consuming. I think it is probably much
easier to get a good fitting valve made from stainless or bronze.
By the way PEEK stands for PolyEtherEtherKetone.

John