My apology to Julian Dyer for misreading his comments about stack
testing. I was thinking in terms of valve "differences due to design,"
versus plain old leakage. Once he explained again that he wasn't
speaking about the faint differences experienced between cross and
round valves, or just valves differing ever-so-slightly between
themselves, and instead was referring to an unknown stack which he
didn't restore himself, then I began to get the picture.
I think it extremely helpful whenever possible to use sample or typical
measurements, instead of saying , "you must use a very accurate gauge
which can measure fractions of an inch of water," or something
comparable to that. Because most offending leaking valves and/or
pneumatics in a Duo-Art will take the gauge down an inch or more. They
are easy to spot. You can almost always hear them leaking. So that
kinda got me off-track, as to what Julian was speaking about.
I do apologize, and Julian is absolutely right about it all the way.