在应用过程中的精度一直是用户所关心的问题，尤其是在给水行业，随着行业的扩展和流量计制作技术的发展，传统的断流取表外送检验的方式已不能满足需要，因此电磁流量计的应用者和制造商都希望有一种在线的电磁流量计检验方法，来替代传统的离线检验方法。 Ensuring the accuracy of electromagnetic flowmeters in the application process has always been a concern of users, especially in the water supply industry. With the expansion of the industry and the development of flowmeter production technology, the traditional method of taking off the meter and sending the meter out of inspection To meet the needs, therefore, the application and manufacturer of electromagnetic flowmeters hope to have an online electromagnetic flowmeter inspection method to replace the traditional offline inspection method.
Users require periodic inspection of flow meters
The accuracy assurance of electromagnetic flowmeters in the application process has always been a hot issue for users. In the past, the calibration of electromagnetic flowmeters had to be sent to a special calibration and verification device for inspection. However, with the development of electromagnetic flowmeter manufacturing technology and the expansion of the application industry, the use of electromagnetic flowmeters is increasing, the caliber is getting larger and larger, and the difficulty of returning to the verification device for verification is becoming more and more difficult. Especially in the water supply industry, due to the large diameter of the pipe and the characteristics of the industry, it is difficult to take out the meter to check the meter and send it out. However, according to the requirements of the ISO9001 quality management system, each enterprise needs to conduct periodic inspections as an electromagnetic flowmeter for measuring instruments. For this reason, the application and manufacturers of electromagnetic flowmeters have been struggling to find an online electromagnetic flowmeter inspection method to replace the traditional offline calibration method. On-line inspection method of electromagnetic flowmeter commonly used at home and abroad in recent years
Large-caliber electromagnetic flow meter on-line verification method: In the 1990s, Shanghai Water Affairs System began to explore online inspection and verification. They used a dedicated analog signal detector to detect the converter, and the sensor inspection was to test the electrode wet resistance. The excitation coil includes Insulation resistance and copper resistance of the excitation connection cable, and indirect methods such as checking the excitation current output by the converter and checking the magnetic field strength. In the pipeline with stop flow condition, enter from the preset hole near the sensor, check the electrode and lining for contamination, deposition and clean. In cooperation with the electromagnetic flow meter manufacturing plant, Shanghai Water Supply Company and Raw Water Company have explored and accumulated more than 300 large-caliber electromagnetic flowmeter inspection experience, and drafted the "On-line Calibration Method for Large-caliber Electromagnetic Flow Meter" from 1997 to 1998. Piloted by Shanghai Public Utilities Administration. Based on this document, the Shanghai Water Affairs Bureau is now formulating local industry standards for the "Online Calibration Specifications for Electromagnetic Flow Meters." The same concept is also mentioned in some literatures, such as the Tokyo Metropolitan Water Works Bureau and Japan's Mitsubishi Chemical Industry's electromagnetic flowmeter field inspection method.
Online electromagnetic calibrator GS9
在欧洲的使用数量最多，其在线检验技术也最成熟，一些主要的电磁流量计制造商基于上述方法还开发出了专用的电磁流量计在线检测仪器，如KROHNE的GS9在线电磁流量计校验仪。 The electromagnetic flowmeter is the most used in Europe, and its online inspection technology is also the most mature. Some major electromagnetic flowmeter manufacturers have also developed special online measurement instruments for electromagnetic flowmeters based on the above methods, such as KROHNE's GS9 online electromagnetic flowmeter. Calibrator. This instrument is a set of calibrators for comprehensive detection of electromagnetic flowmeter sensors and converters, and its detection contents include electrode signals, measurement of analog flow output, measurement of field excitation current, measurement of current and frequency output, coils and electrodes Resistance, etc., and record the data, can also be transferred to a PC. Inspection process: The method of using GS9 is very simple. Just connect according to the cable identification and flow meter (plug and play), and then start the automatic verification. The data will be stored in the internal memory (70 instruments). The data is transferred to a computer for processing. The tester automatically loads the settings of the GK, range, caliber, exciting current, current and frequency output of the meter, and starts measuring the exciting current, detecting the coil and electrode resistance (short circuit or open circuit), checking the signals of the two measuring electrodes, and converting Device current and frequency output check. "Pass" or "fail" diagnosis and storage of the entire calibration process for different parts of the converter. The entire process of calibration is automatically controlled and the calibration data is uploaded to the computer through the RS232 communication port.
GS9 can be directly traced to KROHNE's highest-end calibrator (GS100) and (Netherlands Metrology and Testing Institute NMI), the sensor calibration uncertainty is 0.03%, and the measurement uncertainty of GS 9 is 0.09%. Connect the GS9 to the PC via RS232 at the scene or in the instrument room. Although the above-mentioned online inspection or special diagnostic instrument method is not required to stop the pipeline flow and then test the flowmeter, it still needs the help of external testing equipment to complete the entire inspection. process. Therefore, the development of flow meters with built-in diagnostics and inspection functions is the current development trend of flow meters.
IFC300 electromagnetic flowmeter with self-diagnostic function
IFC300 is an electromagnetic flowmeter that can be self-tested based on the above reasons. All the functions of the online calibrator introduced above are integrated in IFC300. When the user needs to verify the flow meter, the test results can be printed out from the computer through the HART or bus interface. This new type of electromagnetic flowmeter is the latest electromagnetic flowmeter designed according to the requirements of VDI-NAMUR-WIB 2650 guidelines. Compared with the conventional electromagnetic flowmeter converter, this type of converter adds many online diagnostic functions, such as:
* About the process (conductivity, coil temperature, gas contained in liquid, flow state);
* About the application environment (converter temperature, external magnetic field and installation conditions).
The promotion of the online verification method still needs some time and industry
的在线检验方法从诞生到应用正在日趋成熟，但要在全国各行业推广还需要一段时间。 On-line inspection methods of electromagnetic flowmeters are becoming more mature from birth to application, but it will take some time to be popularized in various industries across the country. The biggest difficulty is that the electromagnetic flowmeter is used as a measuring instrument, and its online inspection specifications need to be approved by the national technical supervision department and various relevant industry associations. The above-mentioned schemes and equipment must be cooperated by the manufacturers, users of the electromagnetic flowmeter, and relevant national departments if they are to be approved nationwide. We are glad to see that in the Shanghai water service system where electromagnetic flowmeters are widely used, industry user organizations have joined the technical supervision and manufacturers to complete the industry regulations for online inspection and verification of large-diameter electromagnetic flowmeters and implement them. We look forward to more industries and manufacturers being able to join this technical solution, so that the majority of users of electromagnetic flowmeters can follow the rules.