Fluid flow regulating systems

Fluid flow regulating systems involving systems for controlling the motor speed of fluid pumping devices are disclosed. The speed control systems involve use of a velocity head force sensor that movably responds to the velocity head forces of an air stream delivered by the pumping device, and these movements in the positions assumed by the force sensor are detected and used to control the power delivered to the motor. Temperature change detectors are used in most embodiments to modify the force sensor movements so as to introduce temperature change factors as well as velocity head force change factors into the control of the power circuitry. Force sensor of the pivotal vane, bendable vane and airfoil types are shown, and temperature sensors of the bimetallic and expandable fluid types are also used. A biasing force resistive of the velocity head forces is imparted to the force sensor to establish desired speed levels of operation and bimetallic temperature sensors are used in some embodiments to provide not only the biasing force, but also a variance in the biasing force which is responsive to the changes in temperatures and thus, to introduce the temperature change factors into the force sensor movements.