Ultrasonic Open Channel Flow Meter
Application
The ultrasonic open channel flow meter with weir and flume which used together for measured the flow in the open channels. Mainly application is the outfall of sewage plant and the sewage of enterprises, city sewer and irrigation channels. The instrument produced by our company uses ultrasonic waves through the air, non-contact method to measure. Compare with contact instrument, it has higher reliability and durability in the condition of sticky dirt, corrosive liquid.
Principle
The direct measurement of this series is liquid height of channel and flume. For flow measurement in open channels, installation of weir and flume on the channel, it makes the flow change into level. After measured the level in the weir and flume, then calculate the flow according to corresponding connection of level- flow.
1.The principle of level measurement
The ultrasonic pulses emits by ultrasonic transducer spreads the measured surface through the transmission medium, after reflection, returns to the receiving transducer through the transmission medium, then measured the spreadable time from the emitting to receiving in the transmission medium. According to the sound speed, we can calculate the distance from the transducer to the liquid surface, then we know the level. So we can calculate the distance(D=C*t/2) from probe to reflex surface (the reason of divide by 2 is the sound waves from the transmitter to receiver is actually a back and forth, “D” is distance,“C” is the speed of sound, “t” is time)the liquid level value will be calculate by subtraction.
2. The principle of flow measurement
In the open channel with flow smoothly, bigger flow makes higher level, smaller flow makes lower level.(Figure 2.1). The flow can be calculate by measured the level. In the normal open channel, the connection between the flow and level is effected by the slope ratio and surface roughness of the channel. The throttle caused by the installation of weir slot, produces the stable connection between the flow and level of channel. This connection depends on the structure dimension of weir flume. Note: Reduce the influence of channel as much as you can.
Technical data
