07-06-2013, 02:24 AM
Natural glycerin is what I used on water filtration units, up to and including large RO systems. No problem with the o-rings, and the water washes out any excess, so I had no problems with it. Used it on 316L s/s as well as a few other stainlesses in contact with the fiberglass of the factory RO housings. The high pressure housings I designed were all metal, and still used glycerin for lubing up the o-rings with never a problem. Normally, I chose Viton, which is overkill for ordinary water, but some of the water we designed for was polluted with who knows what, so the decision was to build for worst case, hence the Viton.