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Description of the distance between electromagnetic flowmeter and large motor

On-line inspection method of electromagnetic flowmeter commonly used at home and abroad: On-line verification method of large-caliber electromagnetic flowmeter In the 1990s, Shanghai Waterway System began to explore online inspection and verification. They used a dedicated analog signal detector to detect the converter, and the sensor inspection The test electrode is connected to the liquid resistance, and the in-vibration coil includes the insulation resistance and the copper resistance of the excitation connection cable, and the indirect method of checking the excitation current of the converter output and checking the magnetic field strength. In the pipeline with the stop flow condition, enter the hole from the vicinity of the sensor, check the electrode and lining for contamination, deposition and clean.
If the probability of bubble occurrence in the pipe system is high or bubbles are often mixed, the intelligent electromagnetic flowmeter should be equipped with a gas collecting tank and an automatic exhaust valve upstream of the flow sensor. This technical measure is extremely suitable for measuring medium and large electromagnetic flowmeters that draw raw water from rivers. Important because such applications often contain air bubbles. In recent years, a meter manufacturer has encountered nearly 20 such cases in the original water application field service, and 4% of the failure cases.
The sensor should be grounded separately (grounding resistance 10Ω or less or 100Ω or less). In principle, the grounding should be on the sensor side and the converter grounding should be at the same grounding point. If the sensor is installed on the cathodic corrosion protection pipe, in addition to the grounding ring of the sensor, the thicker copper wire (16m2) is used to bypass the two connecting flanges of the sensor jumper pipe to make the cathodic protection current and the sensor. isolation.
Installation of manual or automatic exhaust valve for electromagnetic flowmeter: The flow of liquid in the pipe may be mixed with air bubbles for various reasons. For example, the flow sensor is installed horizontally at the high point or the second highest point of the pipe system, and it is easy to accumulate in the horizontal pipe. In the upper and flow sensor measuring tubes, the electromagnetic flowmeter may have a phenomenon such as output sloshing. In order to check the cause of the fault and eliminate the accumulated gas, a manual exhaust valve should be installed near the downstream of the flow sensor at the high or second high point for regular inspection and exhaust.

Sometimes the stray current is too large. If the leakage current of the electrolyzer along the electrolyte affects the normal measurement of the electromagnetic flowmeter, the method of electrically isolating the flow sensor from the process connected thereto can be adopted. This method can also be used on cathodic protection lines where the cathodic protection current affects the measurement of the electromagnetic flowmeter.
The distance between the electromagnetic flowmeter and the large motor: The influence of the magnetic field on the electromagnetic flowmeter is greatly different due to the structural material and design of the sensor protection enclosure. For example, some shells are made of ferromagnetic materials such as steel plates, which have better magnetic shielding effect, and have less influence; others are made of non-ferromagnetic materials such as aluminum and glass reinforced plastic, and the influence is large. In addition, the direction between the interference magnetic field and the magnetic field of the flow sensor is different. Now when there is no quantitative analysis and data, there is only some field experience data.
In the past, the calibration of the electromagnetic flowmeter had to be sent to a special calibration and calibration 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 and the caliber is getting larger and larger, and the difficulty in verifying the return to the calibration device is also increasing. The bigger it is. Especially in the water supply industry, due to the large diameter of the application and the characteristics of the industry, it is very difficult to operate by taking off the flow and taking out the checkout. It is time-consuming and laborious, and the magnetic flap level gauge cannot be removed at all. However, according to the requirements of the ISO9001 quality management system, each enterprise needs to perform regular inspection as an electromagnetic flowmeter for measuring instruments. To this end, the application and manufacturer of electromagnetic flowmeters have been struggling to find an online electromagnetic flowmeter inspection method to replace the traditional offline calibration method.

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