Basher trough open channel flowmeter

The Bacher trough open channel flowmeter converts the flow rate in the open channel into the height of the liquid level. Measure the flow rate of water in an open channel. The flow rate of irrigation channels, sewage ditches, and urban sewers. The application fields of open channel flow meters include urban water supply diversion channels, cooling water diversion and drainage channels for thermal power plants, sewage treatment inflow and discharge channels, industrial and mining enterprise wastewater discharge, as well as water conservancy engineering and agricultural irrigation channels.

　　Basher trough open channel flowmeter

The larger the flow in the open channel, the higher the liquid level; The smaller the flow rate, the lower the liquid level. For general channels, there is no definite correspondence between liquid level and flow rate. Because the same water depth and flow rate are also related to the cross-sectional area, slope, and roughness of the channel. Installing a measuring weir groove in the channel, the correspondence between the upstream water level and flow rate of the channel mainly depends on the geometric dimensions of the weir groove, as the gap of the weir or the contraction of the groove is smaller than the cross-sectional area of the channel. The same measuring weir tank is placed on different channels, and the same liquid level corresponds to the same flow rate. The measuring weir channel converts the flow into liquid level. By measuring the liquid level of the water flow in the measuring weir tank, and then reverse calculating the flow rate based on the corresponding water level flow relationship of the measuring weir tank.

　　Basher trough open channel flowmeterpurpose

This instrument is used in conjunction with a measuring weir to measure the sewage flow rate in channels with free flow conditions. When the instrument is working, the sensor does not come into contact with the measured fluid, avoiding contamination and corrosion by sewage in the channel. Used for measuring sewage flow, it has higher reliability than other forms of instruments.

This instrument has data storage function. In addition to storing the flow records of this instrument, it can also connect (4-20) mA signals from other instruments and record them simultaneously (such as water quality measuring instruments: COD, PH, etc., with four additional channels). The stored records can be viewed through the buttons on the instrument panel, printed through a printer, or transmitted through remote communication via RS-232, RS-485, GSM SMS.

This instrument is suitable for monitoring the sewage discharge of enterprises and institutions by environmental protection departments, and for measuring the flow rate of sewage treatment plants.

Display of data errors

When the instrument is powered off, the calendar clock of the instrument runs on the lithium battery on the motherboard. The cumulative flow and historical records of the instrument are also protected by the lithium battery power supply on the motherboard. When the instrument is running, the lithium battery does not consume power. If the instrument is powered off for a long time or for other reasons, causing insufficient voltage of the lithium battery. The calendar clock of the instrument will stop running. After reconnecting, the instrument panel will display the message 'Data error, please check the lithium battery on the motherboard or clear the accumulated flow'.

At this point, it can be eliminated through "calendar clock calibration" in the parameter setting state.

Afterwards, it is necessary to check the voltage of the lithium battery on the motherboard. Normally, it should be between 3V and 3.6V. If it is lower than 2.8V, it needs to be replaced. The lithium battery has an outer diameter of 20mm, a thickness of 3mm, and a nominal voltage of 3V. It is a common button battery in the market. Replace the lithium battery when the instrument is powered on to avoid losing accumulated flow and historical records when removing the lithium battery.

After the above words appear, it is also necessary to check whether the accumulated traffic has been changed. You can view recent historical records and compare them with the current cumulative traffic. If the historical records are not lost, the previous accumulations can be viewed from the historical records.

Technical reference for the construction and installation of measuring weir channels

When choosing the type of measuring weir, consideration should be given to the flow rate inside the channel, the flow state of the water in the channel, and whether free flow can be formed. When the flow rate is less than 40L/s, a right angled triangular weir should generally be selected. For speeds greater than 40L/s, it is generally recommended to use a Bacher slot. If the flow rate is greater than 40L/s and the water level drop in the channel is large, a rectangular weir can be chosen.

If conditions permit, choose the Bacher slot. The water level flow relationship of the Bacher Trough is calibrated experimentally, and there are relatively weak requirements for the upstream channel conditions. The water level flow relationship of triangular and rectangular weirs comes from theoretical calculations, which can easily lead to additional errors due to neglecting some usage conditions.

The measuring weir can be made of fiberglass. The openings of triangular and rectangular weirs are critical dimensions and require accurate processing. The surface facing the inlet side should be smooth. The dimensions inside the Bacher groove should be accurate, and the inner surface should be smooth. The throat section is a critical dimension that needs to be more accurate.

Right angled triangular weir

Processing of right angled triangular weir. Corresponding relationship between water level and flow rate. Please note that the width of the upstream channel where the right angled triangular weir is installed is 600mm, and the height between the apex of the triangle and the bottom of the upstream channel is 250mm. If this is not the case, the water level flow meter should be calculated separately. By using the above-mentioned triangular weir, you can select "right angled triangular weir" in the parameter table "liquid level flow correspondence table" and "weir slot type". The instrument already has a water level flow meter for this weir plate.

Rectangular weir

The water level flow correspondence relationship of a rectangular weir mainly depends on the width "b" of the weir mouth. It is also related to the width of the upstream channel "B" and the height of the weir "p". Rectangular weir, you can select "250 Rectangular Weir", "500 Rectangular Weir", etc. in the parameter table "Liquid Level Flow Correspondence Table" and "Weir Slot Types". There is already a water level and flow meter inside the instrument.