Fume hood exhaust terminal having an ultrasonic motor drive actuator

摘要

A fume hood exhaust terminal for controlling gas flow in an exhaust duct has an electrically powered ultrasonic motor driven actuator for angularly positioning a damper in the terminal. The circuitry of the terminal includes a power failure detection circuit which includes the capability of storing sufficient power to place the damper in a preferred position until power is restored to the exhaust terminal.