Just wanted to pose a question to the tuners and DIY guys who do their own repairs. A common failure I see is with the O-ring on the small end (high side) of a regulator spool. What usually happens is the regulator will begin leaking out of its atmospheric vent. Upon disassembly, this particular O-ring is found to have lost all elasticity and just crumbles to bits. Meanwhile the larger O-ring on the opposite end looks and feels fine.
My best guess is it has to do with the repeated adiabatic heating of the plenum refilling, causing the elastomer to rapidly age and harden. Granted, both O-rings are exposed to the plenum air and therefore experience a temperature rise as the pressure recovers. But perhaps the reason the large O-ring doesn't degrade to the same extent is because the big end of the spool is a larger thermal mass that helps absorb away the heat.
Anyway it occurred to me I've seen this failure again and again on Huma regulators and others sharing a similar design but I don't remember ever running into it on a Ninja paintball regulator. Why? Well, the fundamental operation is the same and in some cases the regulators even have similar dimensions so that doesn't seem to be the reason why. But Ninja uses polyurethane O-rings whereas the brittle O-rings always seem to be the more common Buna-N. If indeed that's the relevant difference, it runs counter to the industry data on O-rings, for which polyurethane has the lowest temperature rating of all common elastomers.
Do any of you guys have experience or knowledge that either substantiates or challenges this theory?
My best guess is it has to do with the repeated adiabatic heating of the plenum refilling, causing the elastomer to rapidly age and harden. Granted, both O-rings are exposed to the plenum air and therefore experience a temperature rise as the pressure recovers. But perhaps the reason the large O-ring doesn't degrade to the same extent is because the big end of the spool is a larger thermal mass that helps absorb away the heat.
Anyway it occurred to me I've seen this failure again and again on Huma regulators and others sharing a similar design but I don't remember ever running into it on a Ninja paintball regulator. Why? Well, the fundamental operation is the same and in some cases the regulators even have similar dimensions so that doesn't seem to be the reason why. But Ninja uses polyurethane O-rings whereas the brittle O-rings always seem to be the more common Buna-N. If indeed that's the relevant difference, it runs counter to the industry data on O-rings, for which polyurethane has the lowest temperature rating of all common elastomers.
Do any of you guys have experience or knowledge that either substantiates or challenges this theory?