Abstract: In a process for measuring the flow of fluids that are subject to temperature changes, particularly for measuring the fuel consumption of an internalcombustion engine with fuel injection, the volumetric capacity of the supply system holding the liquid between the consuming device and the flow meter is automatically increased or decreased corresponding to the change in volume of the fluid caused by temperature. The fluid volume, which increases on heating up and decreases on cooling, no longer causes errors of measurement in the meter.

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.