Float flowmeter - float position measured by sound waves emitted by fixed sender and reflected from float

摘要

In a flowmeter which uses reflected sound, the propagation time of the sound wave is measured. Emission of periodic sound pulses is controlled by a tripping signal, whose period is readjusted every time by a tuning signal whose value depends on the sound pulse propagation time, so that after a few periods the sound pulse propagation time from sender to the float and back is synchronised with the tripping signal period. The tuning signal amplitude is used for the flat position indication. An electric tripping signal employed is an a.c. voltage or current signal, or a triangular oscillation.