的优点 Advantages of electromagnetic flowmeter
① There are no throttling and moving parts in the measuring duct, so the pressure loss is small, energy is saved, and the flow rate of fluid containing particles, suspended solids, etc. can be measured. ② As long as the lining and the electrode are in contact with the medium, only the materials of both are selected, and the purpose of anticorrosion can be achieved; as long as the electrode is not polluted, the accuracy of the meter will not be reduced for a long time. ③ There is a linear relationship between the output current and the flow rate of the electromagnetic flowmeter. And it is not affected by the physical properties of the liquid; therefore, after calibration with water, it can be used to measure the flow of other conductive liquids or solid-liquid two-phase media without correction. ④ SMART converter adopts novel excitation method, low power consumption, stable zero point, high accuracy, flow range up to 100: 1, convenient parameter setting, reliable programming, and self-test and self-diagnosis functions. ⑤ No mechanical inertia, flexible response, can measure pulsating flow.
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. According to the actual application situation and existence of various flow meters used in the past 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. In the measurement process, it was not affected by the temperature and viscosity of the measured medium. Factors influence the advantages. Therefore, in the selection of flow meters, the electromagnetic flowmeter produced by Jiangsu Jinhu Dongxiang Instrument Co., Ltd. was mainly used. We have realized after years of practical application that to make the electromagnetic flowmeter operate safely and stably, we must create better site conditions, and strictly install and debug strictly according to its technical requirements, and implement centralized management to ensure the electromagnetic flowmeter. Work normally to achieve continuous and accurate measurement. The following are the specific practices of our company in the application of electromagnetic flowmeters.
First, the choice of installation position of electromagnetic flowmeter
The installation position of the electromagnetic flowmeter should meet the requirements of the electromagnetic flowmeter for the front and rear straight pipe sections, that is, the length of the upstream straight pipe section of the electromagnetic flowmeter is greater than 5D (D is the pipe diameter), and the downstream straight pipe section is greater than 2D to ensure the axisymmetric distribution of the flow rate and eliminate The resulting measurement error. The installation location of the electromagnetic flowmeter should avoid strong vibration, avoid strong interference sources, and fill the pipeline with water.
的正确安装 Second, the correct installation of electromagnetic flowmeter
1. The installation of the sensor, the installation of the electromagnetic flowmeter is divided into the installation of the sensor and the installation of the converter, especially the installation of the sensor, which requires water stopping, pipe cutting, pumping, welding or punching, which makes the installation work more difficult, and It takes a long time to stop the water, causing some economic losses. In view of 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-disk compensators, eliminating the punching process and the maintenance time of the nozzle. , Especially when the valve is not tightly closed, you can operate with water. After a water outage, it only takes half a day to restore water supply by installing a sensor, which shortens the installation time, reduces the economic loss caused by the water outage, and receives a certain social benefit. 2. Good grounding of the sensor case alone is a necessary condition to ensure the normal and stable measurement of the flowmeter. It is generally believed that the sensor is installed on a metal pipeline, and the pipeline 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 connection flange and the pipe are separated by punching or rubber pads. As a result, the ground resistance of the sensor is greatly increased, which is normal for the electromagnetic flowmeter. Impact on operation. In actual application, we once had an electromagnetic flowmeter that did not work properly after being put into use. Sometimes the flow rate 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 installation of the electromagnetic flowmeter, 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 due to stray current.
Third, the use
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 that of other instruments used before. 1. The electromagnetic flowmeter has high accuracy, good linearity, and stable operation, which improves the accuracy of the measurement and the credibility of the data. It overcomes the problem that some meters are not stable and the measurement data is unreliable. After several on-site comparisons, the errors were within the control range, which strengthened the trust in the meter, ended the unscientific measurement method for calculating the water volume according to the performance curve of the pump, and effectively took the data collected by the meter to avoid 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. 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.
的管理 Fourth, the management of electromagnetic flowmeter
1. Establish the operation file of the electromagnetic flowmeter, including the manufacturer, model, production date, installation location, pipe diameter, calibration time, etc. of the flowmeter to facilitate the maintenance and management of the meter. 2. Strengthen inspections and inspections and carry out regular test calibration. We mainly use two methods, one is to use a relatively high-precision portable flowmeter and electromagnetic flowmeter for measurement comparison; the second is to use a flow meter calibrator to verify the flow converter and check the 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.