Glossary of Terms - V


This is the amount of pressure below atmospheric pressure 0 PSIG or 14.7 PSIA. It increases in value as the vacuum increases (pressure decreases) toward "Absolute Zero" or no pressure. Vacuum values are usually expressed in inches of mercury vacuum ("Hg VAC), inches of water vacuum ("H20 VAC) or millimeter of mercury vacuum (mmHg VAC). A common method of expression of vacuum is to refer to it as 29.92 inches of mercury (29.92 "Hg), which is equivalent to absolute zero (0 PSIA). Sometimes it is referred to as 770 mmHg.

VAR (Volt-Amperes Reactive)

The unit or reactive power as opposed to real power (watts).


The unit of electromotive force (EMF). One volt applied to a resistance of one ohm produces a current of one ampere.

Volt Ampere(s)

The product of the RMS voltage applied to a circuit and the RMS current, in amperes, flowing through it.