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SIlicone vs rubber O-Rings?

  • SIlicone

    Votes: 2 50.0%
  • Rubber (EPDM)

    Votes: 1 25.0%
  • Doesn't matter or depends on the fitting type

    Votes: 1 25.0%

Rubber vs SIlicone O-Rings?

11K views 6 replies 3 participants last post by  DNMock 
#1 ·
Couldn't find any info on this, but which are best to use for water cooling fittings? I'd imagine it's situational or not much difference?

I have a 50-pack of bitspower EPDM rubber O-Rings, and the standard green silicone ones as well as some Phobya red ones. My experience with silicone O-Rings has been that they're much more sensitive to over-tightening or under-tightening, while rubber can be tightened more making the fitting more secure. However, SIlicone can better fill in gaps in a worn out acrylic threaded hole since it's softer. EPDM O-Rings probably last longer though, which is why they're used in rotary seals.

Theories:
  • Silicone O-Rings better suited for acrylic or delrin/POM materials?
  • Rubber O-Rings better suited for metal to metal (like radiators) or fittings you need very tight?
  • Doesn't matter or depends on whether the fitting has proper grooves to prevent over-tightening of silicone O-Rings?
 
#3 ·
Quote:
Originally Posted by DNMock View Post

Rubber is better for normal usage as it makes a better seal than silicone.
Hmm, thanks for the reply. I think they both can make an equally good seal with proper tightness and/or thickness. Silicone is a better gap filler though, and can be finger tightened but too tight and it squeezes out. Rubber feels a lot more solid and probably can make a better seal when tight enough plus it lasts longer, so I think I'll go with rubber O-Rings for most of my build.
 
#4 ·
It doesn't really matter. Neither is going to leak unless you screw something up, in which case both will leak.
 
#5 ·
Quote:
Originally Posted by s74r1 View Post

Hmm, thanks for the reply. I think they both can make an equally good seal with proper tightness and/or thickness. Silicone is a better gap filler though, and can be finger tightened but too tight and it squeezes out. Rubber feels a lot more solid and probably can make a better seal when tight enough plus it lasts longer, so I think I'll go with rubber O-Rings for most of my build.
The rubber ones will vulcanize, making basically a perfect seal while the silicone ones will not. Since the silicone ones don't vulcanize, they are more prone to being leaky, but are much easier to take off and can be reused. Also silicone ones are more resistant to extreme cold and heat.

Basically, you gotta replace the rubber ones when you disconnect the fittings after a long period of time, but you have a much larger margin for error on the machining of parts and how tight the seal must be. If you are confident in the machining on your blocks and fittings and confident in your ability to tighten them down properly, then silicone would be the way to go. Personally, I have next to no confidence in myself to not screw up so the extra idiot proofing rubber provides makes them far superior.
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#6 ·
Quote:
Originally Posted by DNMock View Post

The rubber ones will vulcanize, making basically a perfect seal while the silicone ones will not. Since the silicone ones don't vulcanize, they are more prone to being leaky, but are much easier to take off and can be reused. Also silicone ones are more resistant to extreme cold and heat.

Basically, you gotta replace the rubber ones when you disconnect the fittings after a long period of time, but you have a much larger margin for error on the machining of parts and how tight the seal must be. If you are confident in the machining on your blocks and fittings and confident in your ability to tighten them down properly, then silicone would be the way to go. Personally, I have next to no confidence in myself to not screw up so the extra idiot proofing rubber provides makes them far superior.
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Thanks for the info, I learned something new about rubber. I'll probably use silicone when doing temporary mounting and rubber for more permanent mounting. 50-pack of bitspower EPDM O-Rings is only a few bucks though. This has also convinced me to find some replacement O-Rings for my blocks I've disassembled dozens of times.
 
#7 ·
Quote:
Originally Posted by s74r1 View Post

Thanks for the info, I learned something new about rubber. I'll probably use silicone when doing temporary mounting and rubber for more permanent mounting. 50-pack of bitspower EPDM O-Rings is only a few bucks though. This has also convinced me to find some replacement O-Rings for my blocks I've disassembled dozens of times.
If it's of any condolence, I just learned about it a few months ago while trying to look up the differences in a rubber and silicone radiator hose for my brother's jeep. Had always been told to always replace the rubber gaskets with changing parts that used them, but it wasn't until the radiator hose deal that I knew exactly why
smile.gif
 
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