FredT
Guest
Refigerant rings are HYDROGENATED NITRILE (HNBR, HSN)
Hydrogenated nitrile was developed as an air-resistant variant of nitrile rubber. In HNBR,the carbon-carbon double bonds in the main polymer chain are saturated with hydrogen atoms in a process called hydrogenation that improves the materials thermal stability and oxidation resistance. Flash color on several of these ring compounds are green.
Vitons are FLUOROCARBON (FKM, FPM) Fluorocarbon (FKM) has excellent resistance to high temperatures and a broad range of
chemicals. Permeability and compression set are excellent. Polymer is sold under the tradenames Viton®, Dyneon, and others.
(descriptions from Parker)
As for the colored rings in the reg kits, any ring material can be had with almost any color coumpounded into it on a special order run of a few thousand rings, or rings can be colored in an aftermolding process. I expect very few "flash colored" rings in regulator part kits are special materials or durometer. I expect that most of the flash colors are to keep ham handed repair techs from installing kit rings in the wrong place. The Scubapro MK V uses almost all ring sizes from 10 thru 17, and several are easy to mis-install. Flash colors based on ring SIZE will help minimally trained techs to assemble a rig without mistakes.
As far as regulator assembly goes, I have found very few places where an 70 or 90 duro viton ring won't work and resist extrusion, but I haven't worked much on the "new" SP line yet. I have yet to find a piston first stage regulator that performs much better than the MKV in warm water. The primary "improvement" in the later versions of SP piston regs is the fact that SP still has a vaild patent on those.
FT
