forget about it.
the CV is a relative term regarding the orifice/stem size, small CV with small orifice is the right valve to choose.
swagelok/nupro S, M series metering valve are ok, but not old(discontinued) R needle valve. The R is too big of stem size.
(Nupro 21, 22 series are very good, they are actually swagelok but discontinued models)
As for your chart, it is really easy to tell, concave curve means at lower turns big jump of CV, a convex means small CV increase at lower turns. a convex curve is a typical characteristic of precision metering/needle valve, and it is what you are looking for at the first glimpse.
almost three years I've been trying hard to find and test all the metering valves, and there is a thread about them.
the CV is a relative term regarding the orifice/stem size, small CV with small orifice is the right valve to choose.
swagelok/nupro S, M series metering valve are ok, but not old(discontinued) R needle valve. The R is too big of stem size.
(Nupro 21, 22 series are very good, they are actually swagelok but discontinued models)
As for your chart, it is really easy to tell, concave curve means at lower turns big jump of CV, a convex means small CV increase at lower turns. a convex curve is a typical characteristic of precision metering/needle valve, and it is what you are looking for at the first glimpse.
almost three years I've been trying hard to find and test all the metering valves, and there is a thread about them.