Jim Wilkins wrote:
"Cydrome Leader" wrote in message
news:kjfr4n$g26

There's got to be some sort of "vacuum impedance" or conductance to
volume
matching formula out there, although I can't figure out what's it's
even
called.


http://www.engineeringtoolbox.com/fl...nts-d_277.html

jsw

The ones listed there seen to be for the constant flow of
gas/steam/liquid. The problem is the pressure isn't constant in a pumpdown
scenario.