EIT LiQlyzer Open Channel Flow Meter
Open Channel Flow Measurement Principle
Energy is the underlying basis of liquid flow. Global and specific energy regulate the flow in open channels. The Froude number (Fr) equals one when the particular energy principle states that minimum energy exists.
Fr2=Q2T/g(A3)=1
A specific flow known as critical flow is also produced by this minimal energy situation. When a critical flow occurs, as shown in equation 1, the cross-sectional area and upper width of the flow can be used to compute the flow rate (Q). It is required to establish a critical flow condition that allows the flow to be measured solely by measuring the flow's depth in order to precisely measure the flow in the open channel (producing values for T and A).
How to measure open channel flow?
The height of the liquid as it passes over an impediment (a flume or weir) in the channel is the typical way to measure flow over an open channel. Open channel flow meter use ultrasonic level technology and have a non-contacting sensor located above the flume or weir. The water level is precisely determined by timing the interval between the transmission of an ultrasonic pulse and the reception of an echo.
Open Channel Flow Measurement.
The distinctive channel shapes of flumes and weirs define the water flow.
- Rectangular Weirs,
- V-Notch Weirs,
- Parshall flumes and
- Palmer Bowlus flumes.
| Power supply | 240 VAC 50Hz, 24 VDC 0.2A | |
| Display | Graphical LCD, can be set to Level or Flow | |
| The instantaneous flow rate range | 0.000~999999 l/s, m3/h or m3/min | |
| The maximum of cumulative flow | 99999999.9 m3 (can be user-defined) | |
| Accuracy of change in level | 1mm or 0.2% of measured distance | |
| Resolution | 1mm | |
| Analogue output | 4-20mA into 500 Ohms, corresponding to instantaneous flow rate | |
| Relays outputs | 6 multi-function SPDT relays at most(optional), rated 5A /250VAC/30VDC, High, low and failsafe alarm and control corresponding to instantaneous flow rate or level. also, can be set as the pulse output | |
| Serial communication | RS485, MODBUS RTU protocol | |
| Ambient temperature | -20℃~70℃ | |
| Measure cycle | 1 second (changeable) | |
| Material | ABS | |
| Protection | IP67 | |
| Dimension | 248H*184W*122D (mm) | |
| Specification of sensor | ||
| Range | 4.00 m, 6.00m, 8.00m, 12.00m, 20.00m, 30.00m, 40.00m | |
| Blind zone | 0.20 m, 0.25m, 0.30m, 0.50m, 0.80m, 1.20m, 1.50m | |
| Ambient temperature | -40℃~75℃ | |
| Temperature compensation | Automatic, Integrate in sensor | |
| Pressure range | 0.1 MPa | |
| Beam angle | 8° at 3db | |
| Cable length | 10m standard (can be extended to 1000 m) | |
| Material | ABS, PVC or PTFE (optional) | |
| Protection | IP68 | |
| Dimension | Screw (G2) or flange (DN65/DN80/etc.) | |