Flowmeters are used to measure flow in a hydraulic circuit. As shown in Figure 6.49, flowmeters mainly comprise of a metering cone and a magnetic piston along with a spring, for holding the magnetic piston in the no-flow position.
Flow meters are normally not bi-directional in nature. They in fact act as check valves and block flow in the reverse direction. Initially the fluid entering the device flows around the metering cone, exerting pressure on the magnetic piston and spring. With increase in flow in the system, the magnetic piston begins compressing the spring and thereby indicates the flow rate on a graduated scale.