Abstract: An air conditioning control system for at least two duct sections each with an associated damper comprises at least one master controller for a first pneumatic actuator for one damper and at least one tracking controller for a second pneumatic actuator for the other damper. The master controller comprises a first flow sensor producing a first flow variable signal in response to a sensed flow in the duct section associated with the said one damper. An adjustable reference or bias signal means is provided and a temperature signal is combined therewith to provide a composite signal for comparison with the flow variable signal. A resultant signal after comparison operates the first pneuamtic actuator for the said one damper. A tracking controller comprises a second flow sensor producing a second flow variable signal in response to sensed flow in the duct section associated with the other damper.

Abstract: An air conditioning control system for at least two duct sections each with an associated damper comprises at least one master controller for a first pneumatic actuator for one damper and at least one tracking controller for a second pneumatic actuator for the other damper. The master controller comprises a first flow sensor producing a first flow variable signal in response to a sensed flow in the duct section associated with the said one damper. An adjustable reference or bias signal means is provided and a temperature signal is combined therewith to provide a composite signal for comparison with the flow variable signal. A resultant signal after comparison operates the first pneumatic actuator for the said one damper. A tracking controller comprises a second flow sensor producing a second flow variable signal in response to sensed flow in the duct section associated with the other damper.

Abstract: A damper and control unit for controlling air flow through a conduit comprises a movable damper having a ball-joint connection with the end of an actuating rod. The actuating rod has first and second angularly related portions and the first portion serves as a pivot element for a movable actuating plate, the second portion mounting the damper. The movable or swingable plate is arranged above an expandible and contractable actuating bellows and has a stop chain associated therewith for limiting downward swinging movement thereof in the direction of bellows contraction. The bellows has a supply line leading to the conduit upstream of the damper and a control unit is interposed in the line for determining bellows pressure. Conduit pressure and/or temperature signals are supplied to the control for bellows and damper operation as a function thereof. A seat associated with the damper is uniformly and tightly engaged whereby to seal the conduit due to the floating or ball-joint damper connection with its actuator.

Abstract: A conduit with inlet and discharge ends respectively for receiving a supply of air under pressure and for delivering the air at a lower pressure has a cylindrical configuration and an eliptical butterfly type damper is disposed diagonally therein. The damper turns about an axis intermediate its diagonally opposite ends and the oncoming air stream thus impinges on the upstream face of the damper on opposite sides of the axis and creates a differential force, the said differential force tending to close the damper and constituting a first closing force. A second closing force for the damper is provided by a small bellows supplied with air through a small conduit from the downstream side of an orifice member disposed in the main conduit upstream of the damper. A second and substantially larger bellows serves to open the damper and a small conduit connects the said bellows with a controller supplied with air from an upstream side of the orifice member in the main conduit.

Abstract: An air distribution system supplies conditioned air to at least one zone to be conditioned and comprises a supply duct connected with a diffuser discharging into the conditioned zone. A modulating valve in the supply duct is provided with a bellows actuator for regulating the flow of air into the zone and a secondary conditioning apparatus such as a heater is provided in the supply duct for warming the air before introduction into the zone. The control system for the bellows actuator and for the secondary conditioning apparatus is of the fluidic type with power for the actuator and control system supplied from a total pressure pick-up in the duct. A thermostat for supplying temperature responsive fluidic signals to the bellows and control system is provided with manual adjustments for setting the minimum and maximum flow rates of conditioned air into the zone.