Flowmeters - How They Work
1. Fuel first enters the hydraulic driver, which provides the torque to
rotate the shaft, drum and impeller.
2. The fuel then passes through a stationary straightener and into the
3. The mass of fuel flowing through the rotating impeller causes it to
deflect proportionally against the spring.
4. Impeller deflection relative to the drum is measured by pulses
generated by magnets (attached to the drum and the impeller) rotating past two
5. The time between start and stop pulses, caused by the angular
displacement of the impeller relative to the drum, is directly proportional to
the mass flow rate of the fuel.