Best O-ring to use

[bigdaddy1977]

I am looking at getting new o-rings for my noble 1. My issue is that I love pluid and it makes my o-rings expand, which in turn cracks the glass tank. This has not happened to me personally yet. But my best friend has gone through three tanks this way. I need some help in finding, A. The correct size o-ring. I think it is 11/16 OD x 9/16 ID x 1/16. And B. What is the best type to use that will not swell, or at least have minimal swelling, if there are any? Thanks in advance for the help.

 

[Kent C]

Here's one comprehensive guide on o-rings.... Swelling is due to chemical compatibility, hardness of the material and heat. See page 37 for chem compatibility and check Glycerol and propylene glycol. You'll see silicone and teflon rings do well and a few others.... whereas polyurethane doesn't do well with PG and VG and neoprene don't do so well with PG.

http://www.physics.harvard.edu/services/machineshop/shoplinks/epm_oring_handbook.pdf