Questions about orings in Empire LPR?
I recently replaced the buna orings in the pneumatics of my Resurrection with urethane orings (except for the 3way, couldn't find the right size). The results were pleasing, but when I took it to Fulda Gap last weekend it started having major problems. The 3way began to leak and the LPR had so much pressure that the knob wouldn't turn. Upon taking the LPR apart I found the 003 oring that fits inside the spring had been shredded (not the 003 reg seat), which in turn sent way too much pressure to the 3way and caused its orings to knick when cycling. The problem was resolved by replacing the 003 oring with an original buna and obviously replacing the 3way orings.
My questions: Is that second 003 oring, which fits inside the spring, a dynamic seal? What's the purpose of that oring?
I'm attempting to get the best performance out of the pneumatics. So I'd like to know if there is any benefit to have a urethane oring on that stem, or if I should just save the trouble and leave the buna oring in there.
Thanks in advance!
PS: And if anyone knows where to find urethane 3way orings, I'd be obliged to thank you.
Just changing out o-rings for urethane isn't necessarily a good idea as you found out.
Buna N o-rings, even the same durometer as their urethane replacements, often seal better and more reliably at low pressures. I wouldn't recommend using urethane o-rings in the three-way because they don't tend to be as forgiving at the edge of sealing which is how we run many o-rings in paintball and can cause sealing issues when they get colder. They are 1mm by 3mm o-rings, I've never tried to source them in urethane.
Yes the second 003 is a dynamic sealing o-ring. It separates the input pressure from the output pressure on the backside of the pin/plunger. If it fails you are sending full HPR pressure straight to the pnuematics and to the back of the pin/plunger which is likely why it was very hard to turn the adjuster knob.
In looking through it again, there really aren't any o-rings in the LPR I would recommend changing to urethane or expect you to get any performance increase from doing so...