Abstract: A method and system for providing dosing of fluid is described. The method and system is directed to the control of a plurality of parallel on/off valves which regulate the flow of the fluid. The system includes a plurality of base control valves for delivering a base flow amount. The base control valves are preferably arranged to have binary graduation of their respective flow rates. These base control valves are optionally discontinuously switched on and/or off for delivering the base flow amount. A "timed" valve is varied according to pulse-width modulation techniques to deliver a continuously variable partial flow. The control of the timed valve is effected by electrical circuitry which generates a feedback error signal related to the flow quantity.

Abstract: A volumetric direct gas meter is driven by a servomotor and the rotational speed of the motor is regulated in response to the pressure differential between the inlet and outlet ports of the meter so that the pressure tends to zero.

Abstract: A carburetor for an internal combustion engine comprises a control for maintaining the pressure of the fuel supply through the carburetor constant. The control includes a sensing device, which is preferably a level sensing device, and a fuel feed valve which is automatically operated by the sensing device. The sensing device produces signals which operate the valve to control the rate of fuel supply to the carburetor and, in order to provide an indication of the instantaneous rate of fuel consumption of an engine to which the carburetor is fitted, these signals are also fed to a fuel flow indicator. The fuel flow indicator produces a reading of the fuel flow rate either in dependence upon the frequency of opening of the valve when the opening period is constant, or in dependence upon the period for which the valve is open when the frequency of opening of the valve is constant.

Abstract: Fluid flow metering and control apparatus includes a positive displacement flow meter, a pressure sensor responsive to the pressure difference between the inlet and the outlet of the flow meter and a servo drive mechanism controlled by the pressure difference sensor to maintain the pressure difference between the inlet and outlet side of the flow meter at zero. A hydraulic motor is utilized as the servo drive means.