Abstract: 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.

Abstract: An electronic digital thermostat is disclosed which is capable of use in a pneumatically controlled temperature control system of the type which has a pneumatic supply line which extends to various components of the control system and wherein the control elements of the system are controlled by varying the control pressure that is communicated to such elements. The thermostat is capable of operating in a LAN system environment, and can be retrofitted into unit ventilators and the like as a substitute for a conventional pneumatic thermostat. The thermostat has a processing means that enables sophisticated control to be achieved.