You can use LOX-8 or Krytox family of fluorinated lubricants, but at LOX
temperature they freeze solid like everything else. Cryogenic valves are
often assembled completely dry, with stainless or aluminum parts moving and
sealing against PTFE parts. The key generally in designing parts that move
at cryo is in fact that you can’t have metal scraping past metal protected
with a layer of lube, the way you can at higher temperatures. In a ball
valve this means spherical PTFE seats, in an expansion joint it is spring
energized PTFE seals, in a stem seal it is often as low tech as a PTFE
bushing that is compressed with a nut.
Actuator forces for cryogenic valves can be high.
On Sunday, February 19, 2023, Rocket Pavitra <pavitrapatel.astro@xxxxxxxxx>
wrote:
What are the different options for lubricants to use for valves that carry
cryogenic fluids (liquid oxygen/methane).
I searched online and can't seem to find one that can work well below -112
degree celsius.
Since Liquid oxygen is -183 and liquid nitrogen -210 there must be some
sort of lubricant that is used in valves that operate with cryo fluids.
- Pavitra