This has been a very interesting thread for me. I'm glad that I asked the question! Thanks @Tanks A Lot for the education!!!
I now have a slightly better opinion of Sherwood now. I've been very sour on them for all these years for what seemed like a silly design, even though I've always suspected that the shortened life of the one that I owned and used all those years ago was partially my fault for diving it unpressurized.
Truthfully, I've not had a high opinion of most piston regulators becasue of it either. That Sherwood is the only one that I've ever owned. I see the piston/cylinder as a fairly small tolerance 'delicate' fit that's too fragile for a seawater environment. Especially when compared with the old US Divers SEA regulators that I used to dive with. There the only thing as I recall internal that was exposed was a spring on the ambient side of the diaphragm. That has always seemed like a much more robust design to me, even though there are more "moving parts"
It's been a very long time since I dove with that Sherwood reg... like roughly 30 years. My memory about my thought process is of course, very fuzzy, but I think that I dove it unpressurized in part because of that gas loss, but also in large part just to ensure I didn't have an accidental purge or free flow wasting my precious emergency gas supply! Yes, the post by @inquis + your info about the gas loss from that bubble stream is something that I suppose I never really measured...and I must have wrongfully assumed that the gaseous gold that was leaking out in terms of reduced minutes of bottom time from the tank was something more substantial. I do have to believe, though, that I did have some idea about how much it was. My application was then using it on a 13 cubic foot pony.... and since it wasn't something that I'd get refilled after every dive, I tried to keep it aired up and available for use if there ever was an emergency need. I no doubt monitored the tank pressure and saw it dropping. A little leak from such a small tank is more noticeable than from a large tank. I have no good memory of what my practice was around keeping the reg mounted on the tank or not...but I suspect that I probably removed the regulator for transport and storage. AND before every dive (or diving day) I would pressurize and test it.... so maybe all of that was the larger driver in the gas loss that I would see from that little tank.
One more thought about that little regulator that just popped back to mind as I'm typing this.... and it's nothing to do with the first stage, but I remember the regulator being a very wet breathing thing. Probably another reason that I didn't like that Sherwood regulator!
