On Sun, 10 May 2009 18:33:39 -0500, JohnB wrote:

They have vacuum transducers, and pressure transducers, but I don't see
any of them that cover vacuum and pressure both.

Psst! PSIA (for Absolute) *is* vacuum - true 0 PSIA is a total
vacuum. 14.7 PSIA is 0 PSIG (Gauge), AKA atmospheric pressure at sea
level...

These sensors might not be accurate enough at the bottom of their
range to determine refrigeration system evacuation levels down in the
micron range. You need a different sensor for that.

-- Bruce --