Abstract: A device for measuring the volume of air flowing into or out of an air conditioning duct. The device includes a hood having a top end adapted to cover the air conditioning duct to provide channeling of the air flow into an air flow measurement housing. The air flow measurement housing includes an air flow channel and a manometer for measuring the velocity pressure of air flow through the channel. Movable vanes are provided for varying the cross-sectional area of the air flow channel. Measurement of the air flow volume is accomplished by varying the cross-sectional area of the air flow channel to achieve pre-selected velocity pressure values. Scales are provided which indicate air flow volume based on calculation of the air flow volume at the particular cross-sectional area and air velocity pressure. A series of scales is provided corresponding to a series of increasing velocity pressures so that a wide range of air flow volumes may be determined.

Abstract: A method and system for distributing heated or cooled air from a central pressurized source through a plurality of ducts to a number of spaces utilizing a minimum amount of energy. Each duct has a selectable high-low constant volume fluid flow controller which determines the amount of air flowing into each space according to a thermostat located in that space. A ductstat in the bonnet of the central source maintains the temperature in the bonnet in a narrow ideal desired range.

Abstract: A fluid flow controller is disclosed particularly adapted for maintaining a variable value constant volume fluid flow through a conduit supplying fluid to a zone. A spring biased vane is disposed across the diameter of the conduit to provide a motion signal proportional to the average volume flow pressure across the diameter of the conduit. The motion signal from the vane and a transducer within a zone to which the fluid is being conducted responsive to an environmental parameter in the zone are connected to a controller assembly connected to control an actuator moving a damper within the conduit. The controller is adapted to position the damper to maintain the motion signal from the vane and the signal from the transducer within the controlled zone in balance.This is a continuation-in-part of application Ser. No. 711,066 filed Aug. 2, 1976, now abandoned.

Abstract: A variable value, constant volume fluid flow control device has damper means for regulating fluid flow through a conduit to a zone and damper control means for regulating the damper means comprising fluid supply means for diverting a portion of the fluid flow being controlled to the damper control means, transducer means having a first and a second chamber and being responsive to pressure differentials between the first and second chambers for moving the damper means, means for directing the portion of fluid flow to the first and second chambers, vent means for selectively venting either of the first and second chambers and vane means responsive to fluid flow velocity within the conduit for operating the vent means to operate the transducer means. Bias means are provided for biasing the vane means against a direction of the fluid flow through the conduit such that the vane means returns to a neutral position under conditions of optimum fluid flow velocity.