New water flow sensor products will become mainstream

The use of water flow sensors alone is rare. Most of them are used in various types of water meters, heat meters, and water flow meters to sense and change the flow or velocity of the medium in closed pipes. By processing and displaying the output signals of the signal processing components in the meter, the accumulated flow (ie water consumption), instantaneous flow rate, flow rate at each time period, and heat amount can be obtained. If necessary, the obtained results can also be transmitted externally. Communication.

Under normal circumstances, the flowmeters and meters used for measurement and control of water flow in industrial and agricultural processes, whose sensors usually operate in a narrow range of flow, take the instantaneous flow rate or flow rate of the water in the pipeline as the main monitoring and control target, and the working environment conditions. Usually better; and water flow sensors in water meters and heat meters are obviously different. They require a very wide flow measurement range for the sensor to accommodate different water flow measurement requirements in the same pipe. At the same time, due to the harsh working environment, the grid power supply cannot be used. Therefore, smart electronic water meters, heat meters, etc. must adopt micro-power consumption design and battery power supply, and should have the characteristics of reliable operation in wet and flooded environments.

Mainstream water flow sensors The number of water flow sensors for drinking water and heating water accounts for more than 80% of the total. They represent the basic conditions and characteristics of water flow sensors in many aspects. At present, the number of water flow sensors used in various types of water meters (including mechanical water meters and smart electronic water meters) is particularly large. The annual output is about 60 million units, accounting for about 45% of global production, of which more than 22 million are exported. Taiwan; The annual output of water flow sensors for heat meters is also 3 million.

Among the above water flow sensors, the large-diameter ones are mainly composed of the impeller horizontal wing type and the vertical wing type structure, while the small-diameter ones are mainly composed of the impeller type multi-stream beam rotor type and the single stream beam rotor type structure. This type of impeller-type sensor with a moving mechanism is the most commonly used mainstream water flow sensor in water supply and heating pipes. Others such as volumetric water flow sensors also occupy a small share, and mainly rotary piston structure, usually in the water conditions are better, no impurities in the water use.

Because the impeller-type water flow sensor adopts a rotating mechanism such as a mechanical transmission shaft-type impeller and an impeller box that is proportional to the flow velocity of the pipeline, the mechanism is simple, the manufacturing cost is low, and the long-term stable operation is possible in the case of less impurities in the water. As the rotation of the impeller can not be directly output by electrical signals, such water flow sensors usually use a mechanical totalizer to accumulate and display the amount of water consumption. If the impeller, piston, etc., are directly converted into electrical signals, an electromechanical conversion component must be provided in the sensor to convert the non-electricity rotation into an incrementally encoded electrical signal with a pulse output or an absolute encoded electrical signal with a positional output. To facilitate subsequent signal processing and data transmission and communication.

Pulse-coded signal output needs to use a variety of sensitive components and detection methods, commonly used magnetic susceptibility detection, eddy current testing and switch detection, and several other; position coded signal is usually adopted photoelectric direct reading acquisition.

The impeller-type water flow sensor can work over a wide range of measurement. Because the meter constant cannot maintain good linearity, the measurement range of this type of sensor is limited by the nonlinear characteristics. Currently, computational fluid dynamics (CFD) methods have been used to simulate the flow field of an impeller-type water flow sensor and to optimize the flow characteristics.

The new water flow sensor impeller or piston type water flow sensor has a mechanical movement mechanism, so the shaft system is easy to wear when working, the measurement repeatability is poor, the pressure loss of the pipeline is large, and the electrical signal needs to be output by the electromechanical conversion component. From a development perspective, water flow sensors with mechanical motion mechanisms will gradually exit the stage of history.

New water flow sensors, such as: Electromagnetic, ultrasonic, jet, etc. Water flow sensors Since there are no mechanical moving parts in the sensor, it has a long service life, reliable measurement, and low requirements for water quality conditions. The measurement characteristics can be determined by built-in embedded computers. Making adjustments and corrections is the preferred sensor for smart electronic water meters, heat meters, and meters.

The electromagnetic water flow sensor works with the principle of electromagnetic induction. The output electrical signal of the sensor is proportional to the average flow velocity of the measured water fluid in the pipeline. The electromagnetic water flow sensor has a good linearity and repeatability, has nothing to do with the value of the physical property parameter of the measured medium, and has a small pressure loss, and is a very excellent sensor.

Ultrasonic water flow sensors typically use a time-of-flight differential measurement method. The flow velocity or flow rate in the pipe is proportional to the propagation time and time difference of the ultrasonic wave. Ultrasonic water flow sensor is also a kind of sensor with excellent performance and no mechanical movement mechanism. It also has the characteristics of small pressure loss, good measurement repeatability, wide measuring range, and simple sensor structure.

The jet water flow sensor is a kind of fluid oscillation type sensor. It usually uses the jet wall attachment effect and feedback control principle to work. In a given flow range, the flow rate of the summed fluid in the pipe is proportional to the oscillation frequency of the jet. Jet water flow sensor has good consistency, reliable use, long working life, and strong anti-interference ability. However, the upper limit of the measurement of this sensor is limited by the increase of the pressure loss, and the lower limit of measurement is limited by the increase of the fluid viscosity, which is not easy to oscillate. Therefore, compared with the above two kinds of sensors, the measurement range and pressure loss index of the jet water flow sensor all take a disadvantage.