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.

The usual wire and flume :

Right-angled triangular Weir, rectangular weir and Parshall flume.(figure 2.1)

product-1420-938

Figure 2.1 Usual weir and connection of level-flow

Technical data

Function	Integrated type	Split type
Range	0.1l/s～99999.99 m³/h
Cumulative Flow	biggest：4290000000.00 m³
Max range for level	3m
Accuracy for level	0.5%
Resolution	3mm or 0.1%（bigger）
Display	Chinese LED
Accuracy for Flow	Standard weir:1～5% (meet the requirements of national standard weir and channels) Non-standard weir: 10～30%.
Analog output	(Four-wire system) 4～20mA/750Ωload
Delay output	(optional)two groups :AC 220V/ 8A or DC 24V/ 5A
Power supply	Standard:24VDC 100mA；optional: 220V AC+15% 50Hz
Power supply	(optional)12VDC、battery、solar
Environment Temperature	LED:-20～+60℃，Probe: -20～+80℃
Environment al pressures	Standard atmospheric pressure
Environment humidity	≤90%RH， Non-condensing
Process temperature	-20～80℃；
Process pressures	Standard atmospheric pressure
Communication	Optional:485，232，MODBUS protocol
Protection Grade	LED:IP67 Probe: IP68	LED:IP65，probe:IP68
Cable Probe	No	Standard:10m，The longest:100m
Probe installation dimension	M48x2mm thread + matching nuts
Probe Material	Standard: ABS Teflon material in corrosive environment
Power Consumption	Split type: Power supply:24V, No relay: 100mA Channel 1 of Relay: 120mA； Channel 2 of Relay: 145mA； Channel 3 of Relay: 170mA； Channel 4 of Relay: 190mA； The specific power is as follows: No relay: 24×100mA=2.4W； Channel 1 of Relay: 24×120mA=2.9W； Channel 2 of Relay: 24×145mA=3.5W； Channel 3 of Relay: 24×170mA=4.1W； Channel 4 of Relay: 24×190mA=4.6W； Channel 3 of Relay: 24×170mA=4.1W； Channel 4 of Relay: 24×190mA=4.6W； Integrated type (Four-wire system) Power supply:24V, No relay: 80mA Channel 1 of Relay: 105mA； Channel 2 of Relay: 130mA； The specific power is as follows: No relay: 24×80mA=1.9W； Channel 1 of Relay: 24×105mA=2.5W； Channel 2 of Relay: 24×130mA=3.1W；

Figure and Size Spec.

Open Channel Flow meter

◆Split type

Figure4.1.1 Outline

Figure 4.1.2 Structure of flow meter

◆Integrated type

Figure 4.1.3 Outline

Figure 4.1.4 Structure of flow meter

◆Stilling well Installation

In many scenes, the water surface in the channel has some garbage, foam or other flotsam, which cause measurement errors or no signal. Or the upstream does not have enough length of straight channels and water fluctuations, so we can adopt stilling well installation to resolve it.

Inner Diameter of stilling wall > 50 cm, the wall is smooth without bumps and glitches. After probe installation, the distance ≥0.5m from the probe launch to max water level.

product-935-500