piston rings vs. silicone o-ring

[HOWARDTParticipant @howardt]

Backup rings are used when the radial gap allows the pressure exerted to extrude the ring into the gap. I would not use an o ring in a piston that crossed a port or was used in any thing other than an oil system. There are many special shape and material seals for use in non oil based systems but need to be matched to both media and pressure. Trelleborg sealing systems have plenty of information on their web site if you need to get more confused!!

Howard

[Ian S CParticipant @iansc]

Rubber has similar compression to water!1

Ian S C

[Peter KroghParticipant @peterkrogh76576]

Ian, it depends on the type of rubber. Some are denser than others. And here's the biggie; water does compress! Not much but enough that the dielectric constant changes measureably. Back in the early '70s we did the experiments while investigating the use of pure water for high voltage insulation. Neat stuff.

Pete

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