Ultrasonic flow meters use high-frequency sound waves, above 25 kHz, for accurate measurements without audible noise, generated by vibrating piezoelectric crystals.An ultrasonic flow meter consists of at least one sensor and transducer pair. Each member of the pair can act both as a transmitter and a receiver.
When in receive mode, an ultrasonic wave passing through the fluid creates vibration in the piezoelectric crystal, and an electrical impulse is generated.
When in transmit mode, an oscillating electrical current creates a vibration in the piezoelectric crystal, and an ultrasonic wave is sent through the flowing fluid.
A pulse that travels with the flow, takes less time to make the trip than the pulse returning in the opposite direction, or against the flow.
The difference in this time of flight between the two pulses is directly proportional to the flow velocity. Since the volumetric flow rate is equal to velocity times the cross-sectional area of the pipe, which is fixed at the flow meter, this measurement yields the flow rate.
Музыка
Фильмы
ТВ Шоу
Категории видео
