Abstract: A fume hood exhaust terminal for controlling gas flow in an exhaust duct has an electrically driven linear actuator for angularly positioning a damper in the terminal. Drive circuitry employed in the preferred embodiment prevents the possibility of shorting out the actuator motor in the event of an input signal condition which would attempt to operate the motor in two directions simultaneously. The circuit also 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: A thermostat control having improved user controls wherein an analog version contains a binary coded switch for selectively setting a setpoint temperature. The binary coded switch is configured to have discrete positions corresponding to a plurality of setpoint temperature settings. It contains, among other things, a resistor network configured to produce a setpoint signal indicative of the binary coded switch position and a setpoint adjust switch for setting the binary coded switch position. Also, digital version having a man-machine interface port, wherein point information from a controller can be viewed and modified with the thermostat control device controls when a hardware passkey is inserted into the man-machine interface port.

Abstract: Apparatus for monitoring the speed of movement of at least one sash door of a laboratory fume hood is disclosed. The speed of movement of a sash door is detected and an alarm signal is generated if the speed of movement exceeds a predetermined value while increasing the size of the uncovered opening of the fume hood.

Abstract: A HVAC system automates the process of calibrating the individual branch flows of the system. For each branch of the system, a damper is closed and flow values at the output of the prime mover and at the input of the damper are measured. The damper is then opened 50% and again flow values at the output of the prime mover and at the input of the damper are measured. A flow coefficient, which correlates the flow difference measured at the output of the prime mover with the flow difference measured at the input of the damper, is then determined. The flow through each damper of each branch is calibrated in this manner, resulting in an overall balancing of the HVAC system. The automated process of branch flow calibration eliminates the tedious and time consuming process of both manual steps of measuring the branch flows and determining the flow coefficients as was performed in the prior art.

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.