VOLUMETRIC VACUUM CONTROL

摘要

A vacuum packaging apparatus includes a novel vacuum sensor system (58) having first (90) and second (92) sensors in communication with a control circuit (54). The sensors are provided to detect first and second preset vacuum levels as a container is being evacuated. The control circuit (54) further includes a timer (55) for measuring the elapsed time between detection of the first and second preset vacuum levels. The control circuit (54) computes an additional time period necessary to reach a target vacuum level after reaching the second preset vacuum level by multiplying the elapsed time between the first and second preset vacuum levels by an algorithmic factor stored in the control circuit (54). The algorithmic factor is a numerical constant that is derived for a particular pump type, and is based on the pump characteristics and selected values for the first and second preset vacuum levels and the target vacuum level.