Hi everyone, new guy here. Sealing is my business, i handle o-rings everyday and stock thuosands of them in different durometer and elastomers. Can help clear up any questions and procure the right sizes.
Well maybe you should step up to the plate and put together a reasonable replica of the extra seal pack that came with the Drozd when it was new. They only included the 3 main seals, how about 6, 10x2's, 4, 2x6's, both Bn70, and 2 007's, PU90, those valve seals.
Since you are an expert, here is the only little tiny issue: Most PU90 rings are the millable gum type, and not cast urethane. The original seals are cast urethane, the only difference between millable gum, and cast urethane, is one of cost, cast costs a lot more, and they are identical for all intents and purposes, EXCEPT THAT millable gum should not be used with Co2. This means that the much more expensive cast urethane rings are much harder to come by, since very few applications involve Co2, but ours, however, is one of them. In fact, though, I have always just replaced them with the millable gum type, and I have never had any problems with them. HOWEVER, I don't actually shoot Co2 very often, and they do turn more opaque, and seem to get a little bit more brittle, or get harder, after a while. Again, that's never really caused one to fail on me, though. I do put new ones in whenever I get into the valve head for anything, though, just because I can.
Most of us never bother with Co2, so it wouldn't make any difference to us, but technically speaking, if someone does use Co2, the millable gum seals aren't rated for that at all, they are supposed to be cast urethane.
Now if you are an expert on O-rings, you should know what I am talking about, and if you don't, you probably should read what the manufacturers have to say about the difference between millable gum and cast urethane is. If you want to take your original cast urethane valve seal out, and compare it to one of the millable gum type in your own inventory, you'll see that the cast one is more translucent, and it's a dark brown color, and the millable gum one will be more opaque, and a sort of yellowish green sort of color. They are completely different, as you'll see. If you have to include millable gum rings, you might want to include an advisory against using Co2. It probably won't ever make any difference, mine have never failed, but it never hurts to cya. And like I siad, most of us shoot HPA, anyway.
