Open channel flowmeter

Mass Creation UOFM21-DR Seriesultrasonic waveOpen channel flowmeterWorking Principle:
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 converts the flow rate into liquid level, and by measuring the liquid level of the water flowing through the measuring weir, the flow rate can be calculated based on the corresponding water level flow relationship of the measuring weir.

Common types of measuring weirs:

The measuring weir channel converts the flow into liquid level
The water level flow relationship of the measuring weir can be found in the national metrological verification regulation "Open Channel Weir Flow Meter" JJG711-90.
Each type of measuring weir has its own fixed water level flow correspondence. When determining the water level flow relationship, the triangular weir requires parameters such as channel width B, opening angle, and upstream weir height p; The rectangular weir should have parameters such as channel width B, opening width b, and upstream weir height p; The Bacher groove only requires a parameter b with throat width.

Mass Creation UOFM21-DR SeriesPrinciple of Ultrasonic Liquid Level Measurement:
This instrument uses ultrasonic echo ranging method to measure liquid level. The probe is fixedly installed above the water level observation point of the measuring weir (the location of the water level observation point can be found in the weir structure description). The probe emits ultrasonic waves, which are then reflected by the liquid surface and received by the probe. The distance between the probe and the liquid (object) surface is proportional to the time the ultrasonic waves have passed
H= CT/2 ; Distance [m]=Time x Sound Speed/2 [m]
Temperature compensation formula for sound velocity: Environmental sound velocity=331.5+0.6 x temperature

Open channel flowmeterThere are many varieties, and the common one is the weir styleOpen channel flowmeterAnd groove styleOpen channel flowmeterTwo major categories. A flow meter that can be used to measure free surface natural flow in non full tube open channels. A waterway with non full pipe flow is called an open channel, and measuring the flow rate of water in the open channel is calledOpen channel flowmeter(open channel flow meter)。Open channel flowmeterIn addition to circles, there are various shapes such as U-shape, trapezoid, rectangle, etc.Open channel flowmeterAll urban water supply channels in the application field; Water diversion and drainage channels, sewage treatment inflow and discharge channels in thermal power plants; Water discharge from industrial and mining enterprises, as well as channels for water conservancy projects and agricultural irrigation.

ultrasonic waveOpen channel flowmeterThe main component, the Bacher trough (also known as the Bacher trough), is an auxiliary equipment used for measuring open channel flow. Widely used in 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.
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 volume, it has higher reliability than other forms of instruments. This instrument is equipped with an RS232 serial port that can be connected to a computer or other data collector, as well as a modem or wireless communication module, to achieve wired or wireless remote communication.

UOFM21-DR series ultrasonic technology for mass creationOpen channel flowmeterProduct Features:
1. Can measure the flow rate of non full tubes (round tubes, egg shaped tubes, or other shaped tubes).

2. Measurable channel (circular channel, rectangular channel, or other irregular channel) flow.

3. It can measure the natural flow of rivers and streams.

4. Can measure the flow rate of sewage discharge channels or pipelines (sewers).

5. Can measure forward and reverse flow velocity and flow rate.

6. Can provide instantaneous flow values and cumulative flow values.

7. Optional output signals: RS-485, Modbus, 4-20Ma current signal, and multi-channel switch quantity.

8. Sensors can work for a long time in harsh environments and sewage quality.

9. Optional SMS or GPRS wireless module for remote telemetry.

10. The sensor housing is made of polycarbonate, ABS or polytetrafluoroethylene (standard is ABS plastic), with a protection level of IP68.

11. Optional built-in automatic temperature compensation.

12. The blind spot can be adjusted to block interference signals near the probe.

UOFM21-DR series ultrasonic technology from Qunchuang TechnologyOpen channel flowmeterThe measurement of fluid flow in many non full water, high flow (or low flow), naturally flowing free surface states is called open channel flow detection. Due to the large or small flow rate in open channels, there is often some corrosiveness or impurities carried in the fluid, making it difficult to detect the flow rate using a general pipeline flowmeter. For example, in the fields of industrial enterprise drainage, hospital wastewater, agricultural irrigation water, urban groundwater drainage, etc., open channel flow detection, especially ultrasonic non-contact open channel flow meter, is an optional flow detection instrument.

The UOFM21-DR series ultrasonic open channel flow meter from Qunchuang Technology is paired with the corresponding Bacher tank. It uses the propagation law of ultrasonic waves in the air to measure the liquid level height and continuously transmits the liquid level information to the host. The host automatically measures the instantaneous flow rate and cumulative flow rate through the computing system and stores them. This instrument uses advanced technology to complete flow detection without contact with fluids, and has liquid level measurement, control, data transmission, and human-machine communication functions. This machine is a flow measurement instrument that integrates ultrasonic transmission and reception sensors, servo circuits, temperature compensation sensors and compensation circuit units, integration host, display, control signal output, and serial data or analog output units.

Main technical parameters of UOFM21-DR series from Qunchuang Technology:

1. Measurement range: 0.1L/S~10M3/S

2. Accumulated traffic: 9999999999M3

3. Ranging range: 0-3M

4. Distance measurement accuracy: 0.25%

5. Flow accuracy: 1% to 5% (depending on the type of weir plate)

6. Blind spot: 0.2-0.35M

7. Resolution: 1mm

8. Instrument display: Equipped with LCD display for instantaneous flow meter and cumulative flow meter (optional display of liquid level height)

9. Analog output: 4~20mA output instantaneous flow rate

10. Digital output: RS485 interface, ModBus protocol or customized

11. Power supply voltage: DC12V, 24V or AC220V, can be powered by solar cells

12. Environmental temperature: -20 to+60 degrees

13. Protection level: IP67 (aluminum alloy) IP65（ABS）

14. Explosion proof grade: intrinsic safety explosion-proof (optional)

15. Installation method: bracket or flange installation

16. Maximum installation distance: less than 50 meters (split type)

UOFM21-DR series ultrasonicOpen channel flowmeterThe external dimensions and flow range of the Bacher trough:

UOFM21-DR series ultrasonicOpen channel flowmeterThe instrument controls the probe to emit and receive ultrasonic waves. Convert to liquid level (unit: meter) according to the process in Figure 8. Then, by checking the water level flow meter, convert the liquid level into flow rate (which can be expressed in liters per second or cubic meters per hour).
A water level flow meter is a set of data stored in an instrument. You can input data into the instrument's memory through the buttons on the instrument panel. The water level flow meter of this instrument is stored at equal liquid level intervals. The position of "cumulative traffic reset time" is displayed.

There are several issues to consider when installing a measuring weir, otherwise it will affect the accuracy of flow measurement:

• The centerline of the measuring weir should coincide with the centerline of the channel to prevent water flow from deviating when entering the measuring weir.

• After the measuring weir channel is filled with water, the flow state of the water should be free flowing. The water level downstream of triangular and rectangular weirs should be lower than the weir crest; The submergence degree of the Bacher trough should be less than the specified critical submergence degree.

• The upstream of the measuring weir should have a straight section greater than 5 times the width of the channel, so that the water flow can enter the measuring weir smoothly. There is no lateral deviation or the impact force formed by the slope of the channel.

• The installation of the measuring weir groove on the channel should be firm. The connection with the side walls and bottom of the channel should be tight and not leak water. Make all the water flow through the measuring part of the measuring weir. The measuring position of the water measuring weir plate is the weir mouth; The measuring part of the measuring tank is the throat section inside the tank.

• ultrasonic waveOpen channel flowmeterThe probe can be directly installed above the water level observation point of the measuring weir. The side of the probe that emits sound should be aimed at the water surface. You can place a level ruler on top of the probe and align it with the water surface by leveling the cover. The water level observation point of Bacher trough is located at a distance of 2/3 of the contraction section of the throat; Triangle weir and rectangular weir are located on the upstream side, 3-4 times the maximum water depth passing through the weir plate.

• When installing the probe, pay attention to the blind spots of ultrasonic waves. When the highest possible water level occurs, the distance between the probe and the water surface should not be less than the blind spot distance (0.5 meters).

• The three inlet holes at the bottom of the transmitter have a diameter of 8mm. Please use cables with a diameter of 6mm to 8mm;

• When placing transmitters outdoors, the compression nut of the inlet hole must be tightened, otherwise the waterproof effect will be greatly reduced;

• If the inlet is not in use, please insert a 6mm to 8mm cable head into the inlet hole and tighten the clamping nut;

• Due to the use of LCD liquid crystal in the transmitter. Although the LCD used by our company is wide temperature and UV resistant, prolonged exposure to sunlight can still affect the lifespan of the LCD. So, when placing the transmitter outdoors, please try to place the LCD facing north.

  UOFM21-DR series ultrasonicOpen channel flowmeterSolar power supply systems can be chosen to meet the needs of remote mountainous areas.

• 

• 

• 

• 

•