Page 7 in the PV350 user manual [[...]] shows a vacuum range of (0-29.9 in-Hg) or (0-76 cm-Hg).

Just below that: 'Output: 1mV per unit' and 'Resolution: 0.1 in mV range'

So, one can expect 17 inches of vacuum to display as 17mV, or 17.5 inches of vacuum to... Login to read more.