Sash door position sensing apparatus for controlling air flow through laboratory fume hood, has sensor for determining opening of cabinet, based on rotation of shaft

摘要

A rotary position sensor (84) is mounted on a cabinet (64) at a position above and adjacent to a sash door (62). A lever arm (88) is attached to the output shaft of sensor and sash door, such that when the sash door is moved between closed and opened positions, the shaft is rotated to predetermined angle and the sensor outputs resistance value which is proportional to the size of uncovered opening in cabinet. An Independent claim is also included for air flow controlling apparatus.