Dayu Split-Type Ultrasonic Open Channel Flow Meter for Rectangular Channel Flow Monitoring

　　Typical flow monitoring applications include natural rivers, main irrigation canals, branch irrigation canals, hydropower station discharge, urban inland rivers, and urban stormwater/wastewater flows. Different flow instruments are selected based on the measurement environment.

　　The following is a standard rectangular channel flow monitoring example:

　　Channel characteristics: channel width 59 cm, height 43 cm;

　　Channel type: rectangular flow passage

　　Selection details: For a rectangular flow passage, an ultrasonic open channel flow meter can be used. If higher accuracy is required, a Parshall flume can be paired for measurement, achieving a flow measurement accuracy of 1–5%. If accuracy requirements are less stringent, a standard rectangular weir can be used for monitoring, with a flow measurement accuracy of 10%. This measurement point uses the rectangular weir tank method; however, according to the national standard dimensions for rectangular weirs:

　　Rectangular weir plate structure and precautions:

　　This measurement point adopts the minimum national standard rectangular weir tank dimensions: b=250, B=500, h=250, P=100. During fabrication of the weir tank, provided that the dimensions do not affect the flow measurement accuracy, B should be adjusted to 590 mm and h to 330 mm as appropriate, so that installation is better suited to the site conditions.

　　Installation requirements for the flow instrument sensor:

　　1. Install the sensor about 1 meter upstream of the rectangular weir outlet, at a location where the water flow is stable;

　　2. The installation height of the sensor should be at least 20 cm above the highest water level;

　　3. The sensor mounting thread is M48*2, and the mounting bracket opening diameter should be 50 mm;

　　4. During installation, a rubber gasket and nut should be added to the sensor to secure it and provide vibration isolation.

　　Installation precautions for the flow transmitter:

　　1. The sensor cable should be routed through a protective conduit to prevent accidental damage;

　　2. The transmitter (i.e., flow totalizer) must be enclosed in a waterproof enclosure to prevent water ingress;

　　3. The transmitter must be properly grounded to avoid interference.

　　The following are site installation photos:

　　Figure 1: Fixing and installation of the rectangular weir plate   

       Figure 2: Fixing and installation of the sensor bracket

Figure 3: Completed installation