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Application of electromagnetic flowmeter

(Summary description)  Flow is a commonly used process control parameter in the industrial production process, and is an important production technical indicator for the water supply industry. The accuracy of flow measurement will affect the correct calculation and credibility of important indicators such as cost accounting and energy consumption. Therefore, it is very important to choose a flow meter with high quality, stable operation and accurate measurement.

Application of electromagnetic flowmeter

(Summary description)  Flow is a commonly used process control parameter in the industrial production process, and is an important production technical indicator for the water supply industry. The accuracy of flow measurement will affect the correct calculation and credibility of important indicators such as cost accounting and energy consumption. Therefore, it is very important to choose a flow meter with high quality, stable operation and accurate measurement.


  Flow is a commonly used process control parameter in the industrial production process, and is an important production technical indicator for the water supply industry. The accuracy of flow measurement will affect the correct calculation and credibility of important indicators such as cost accounting and energy consumption. Therefore, it is very important to choose a flow meter with high quality, stable operation and accurate measurement.

  With the development of science and technology, new types of flow meters are constantly emerging, with a wide variety and different performances, and their use conditions and technical parameters are also different. For users, they should first understand the performance characteristics of the flow meter and make the correct choice in accordance with the operating conditions of the specific application of the unit.

  Our company has used many different types of flow meters in flow measurement for many years, such as turbine flow meters, ultrasonic flow meters, plug-in and measuring tube electromagnetic flow meters, etc. Among them are domestic and imported meters. Performance and use effects are also different.

  In order to measure the water supply more accurately, our company has invested a large amount of money in recent years to upgrade the original flow meter. In the preliminary selection work, we based on the various flow meters used in the past. The actual application situation, existing problems, installation difficulty, performance-price ratio, and other issues were carefully analyzed and compared, and the electromagnetic flowmeter was considered to be sensitive, linear, and accurate. During the measurement process, it was not affected by the measured medium. Although the installation is relatively complicated, we have adopted a new installation process for the flowmeter installed on the cast iron pipeline, which reduces the installation difficulty and reduces the water stop time. Therefore, in the selection of flow meters, the electromagnetic flowmeter produced by Kaifeng Instrument Factory was mainly selected. We have realized after years of practical application that to make the instrument operate safely and stably, we must create better site conditions, and strictly install and debug strictly in accordance with its technical requirements, and implement centralized management to ensure the normal operation of the flowmeter. Achieve continuous and accurate measurement. The following is our company's specific practices in the application of electromagnetic flowmeters (Take E-mag electromagnetic flowmeters in Kaifeng Instrument Factory as an example) for discussion.

  I. Choice of Instrument Well Location

  The position of the instrument well should meet the requirements of the flowmeter for the straight pipe sections before and after, that is, the length of the straight pipe section upstream of the flowmeter is greater than 5D (D is the pipe diameter), and the straight pipe section downstream is greater than 2D to ensure the axisymmetric distribution of the flow rate and eliminate the Measurement error.

  The installation location should avoid strong vibration, avoid strong interference sources, and the pipeline should be filled with water.

  Second, the correct installation of the instrument

  1, sensor installation

  The installation of the electromagnetic flowmeter is divided into the installation of the sensor and the installation of the converter. In particular, the installation of the sensor requires processes such as water stopping, pipe cutting, pumping, welding, or punching, which makes the installation difficult and requires long-term water stopping. Cause some economic loss. In response to this situation, when we installed the flowmeter on the cast iron pipeline, we adopted a new process method, replacing the traditional short tubes A and B with two single disc compensators, eliminating the punching process and the maintenance time for the nozzle. , Especially when the valve is not tightly closed, you can operate with water. After the water is stopped, it only takes half a day to restore the water supply by installing a sensor, which shortens the installation time, reduces the economic loss caused by the water out, and receives certain social benefits.

  2. Good grounding of the sensor case alone is a necessary condition to ensure the normal and stable measurement of the flowmeter.

  People generally think that the sensor is installed on a metal pipe, and the pipe is buried underground, and the pipeline is very long. It is itself a large ground electrode, and the instrument does not need to be grounded. However, two problems have been ignored. One is that the pipes are generally treated with anticorrosion, and the other is that the connecting flange is separated from the pipe through a mouthpiece or a rubber pad, which causes the ground resistance of the sensor to increase greatly and to the normal operation of the flowmeter Make an impact.

  We used to have a flowmeter that did not work properly after being put into use. Sometimes, the flowmeter was not displayed, and even an empty pipe alarm was displayed. At that time, there was no result in finding the cause according to the fault phenomenon. Later, the sensor was separately grounded, and the fault phenomenon disappeared immediately. So far, the operation is normal.

  Therefore, after the flowmeter is installed, the grounding resistance should be measured. If the resistance is too large, it is best to make a grounding electrode to reduce the interference potential caused by stray current.

  III. Usage

  After several years of actual operation and observation and comparison, we believe that the operation of the electromagnetic flowmeter in our company's production is better than the work of other instruments used before.

  1. The electromagnetic flowmeter has high accuracy, good linearity, and stable operation, which improves the accuracy of measurement and the credibility of the data, and overcomes the problem that some meters are not stable and the measurement data is not credible. After several on-site comparisons, the errors were within the control range, which strengthened the trust in the meter, ended the unscientific measurement method of calculating the water volume based on the pump's performance curve, and effectively took the data collected by the meter to avoid the Human Factors.

  2. The electromagnetic flowmeter has a simple structure, the sensor has no moving parts, and there is no measurement error or instrument failure due to mechanical motion wear or foreign matter entanglement, so the failure rate is very low, and the maintenance amount is greatly reduced, thereby saving a lot of manpower and material resources.

  Since 1992, our company has installed and used 18 electromagnetic flowmeters produced by Kaifeng Instrument Factory. So far, only one instrument converter has a faulty installation position and the converter circuit board has failed, and the rest are working normally.

  3. The electromagnetic flowmeter has a variety of interface circuits, which can be easily connected to a data acquisition terminal or computer to achieve data collection, analysis, and management automation. All the flowmeters of our company are connected with the dispatching system of the head office. The raw data of the water supply and source water quantities have entered the computer collection and transmission network, which has greatly improved the authenticity and fairness of the measurement test data. Standardization and standardization have laid a solid foundation.

  Four, flowmeter management

  The number of flowmeters installed and used by our head office is relatively large, and the installation locations are scattered. The source water and water supply of the plants affiliated to the head office are basically calculated according to the flow meter. In order to facilitate management, the metering and testing center of the head office is responsible for the maintenance, debugging, and verification of all flowmeters for unified management.

  1. Establish the flowmeter operation file, including the flowmeter's manufacturer, model, production date, installation location, pipe diameter, calibration time, etc., in order to facilitate the maintenance and management of the meter.

  2. Strengthen inspections and inspections and conduct regular test calibration. We mainly use two methods, one is to use a relatively high precision portable flowmeter and electromagnetic flowmeter to perform measurement comparison; the second is to use a flow meter calibrator to verify the flow converter and check various items Whether the technical indicators are correct and test data are archived.

  3. Compare the test data with the previous test results, carefully analyze the suspicious data that appears, find possible causes, deal with them in a timely manner, and make an analysis report of the operation of the flow meter.

  The above is our superficial understanding and is for reference only.

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