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由于超声波在穿过流动的液体时,沿顺流方向和沿逆流方向的传播速度是不同的,时差式流量计就是利用这一原理制成。 由美国康创公司设计和制造的990型系统差式超声波流量计是采用宽脉冲传感器技术,配合可变频率传送线路,使传感器可适用于不同的管材和管径。传感器内的石英会发出一种与管材谐振的频率,超声波信号在管壁内轴向运动后再传送至另一传感器,增强的信号密度使这种流量计适用于不同温度、流速、含汽泡率和固体杂质的液体。采用金属传感器可计量高温度的液体并提高长期的稳定性/线性。它适用于石油化工,冷气/热水系统,水电及自来水计量,其精度为1％～2％,校正后的精度可达0.25％～1％。比传统的计量计有许多优点:如外缚式安装不用修改管道设计,数字及图形显示当时流量及总流量;可靠性高,不接触液体,无须维护保养;灵敏度高(0.304 8mm/s);可测量管道中的液体成份;有自诊功能,显
As the ultrasonic wave passes through the flowing liquid, the propagation velocity along the downstream direction and the counter-current direction are different, and the time-difference flowmeter is made using this principle. The Model 990 System Differential Ultrasonic Flow Meter, designed and manufactured by Comtec, USA, uses a wide pulse-sensor technology with a variable frequency transmission line to adapt the sensor to different tubing and pipe diameters. Quartz in the sensor emits a frequency that resonates with the tube. The ultrasonic signal is transmitted axially to the other tube after the tube is moved. The enhanced signal density makes this meter suitable for use at different temperatures, velocities, Rate and solid impurities in the liquid. Metallic sensors measure liquids at high temperatures and improve long-term stability / linearity. It is suitable for petrochemical, air / hot water systems, hydropower and tap water measurement, the accuracy of 1% to 2%, the corrected accuracy of up to 0.25% to 1%. Than the traditional metrology has many advantages: such as the external installation of the pipeline without modifying the design, figures and figures show the current flow and total flow; high reliability, no contact with the liquid, no maintenance; high sensitivity (0.304 8mm / s) Can measure the liquid composition of the pipeline; have self-diagnosis function, significant