[162] Flow meter
The flow of oil to be
measured passes through a movable orifice. The orifice consists
of a fixed cone and a hollow piston mounted on a spring. The
piston is pressed against the spring in proportion to the flow
rate concerned. The measuring error of this type of flow meter is
approx. 4%. Measuring turbines, oval disk meters or toothed-wheel
gauges are used when higher accuracy is required.