When asked where our materials are used, I normally say ‘ wherever there is extremes of conditions, whether that be extreme temperatures, extreme pressures, extreme speeds, extreme of media (corrosive or combustible materials) or a combination of them all.
There is probably no application where this statement is more relevant and applicable in its entirety than within space rockets!! And I don’t mean the ones built with toilet roll tubes by your 5 year old, I mean the real deal, you know, ones that go into space and not just across your kitchen.
AFT Fluorotec were recently commissioned by a space technology company. A company who researches, designs and manufactures cutting edge rockets using environmentally friendly propellants (what?? Eco friendly rocket fuel? – never!) to deliver payloads into space
Principally they needed a number of seals designed to control liquid oxygen (extreme media) delivery to the business end of a rocket engine. Just a valve? On Paper it looks exactly similar to so many valves we make, the only difference being this one is working at minus 198OC (extreme of temperature), attached to a rocket that is accelerating at 90m per second per second (Extreme of speed)… pulling a lot of G’s and hitting mach 1 pretty quick too!!. Oh and what was the last extreme – Pressure, That’s right I almost forgot, it’s at 150bar. Not a lot going then really…!!
However this was an easier application that you might think from the brief. The reason being one very special material that is an exceptional choice for performance and retained physical properties at very low temperatures, is also a uniquely special material for use with liquid oxygen – Polychlorotrifluoroethylene or PCTFE to use the acronym which certainly rolls of the tongue a bit easier.
PCTFE has one of the highest limiting oxygen Index (LOI). It is resistant to oxidisation because it does not have any hydrogen atoms (C2CIF3)n. It also has excellent chemical resistance and exhibits properties such as zero moisture absorption and non-wetting.
In ambient conditions PCTFE is not the best seal material for a dynamic application. However once you get to cryogenic temperatures, there is literally no fluoropolymer (technically it’s a chlorofluoropolymer) that performs better.
Being a processor of the first choice seal jacket material of PCTFE and with dozens of years experience in seal design, spring selection etc the application that seems daunting becomes less tricky than it first seems.
If you have such requirements please get in touch.
