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Intelligent electromagnetic flowmeter

Jan 14, 2019


Intelligent electromagnetic flowmeter


What is a smart electromagnetic flowmeter?

 The intelligent electromagnetic flowmeter is an all-round intelligent flowmeter developed and developed by advanced technology at home and abroad. It is very different from the old-fashioned analog or non-intelligent electromagnetic flowmeter, especially in measurement accuracy, reliability, stability, use function and Service life and other aspects.

Intelligent electromagnetic flowmeter refers to the flowmeter with intelligent data transmission such as HART, 485, MODBUS protocol, Profibus-DP, etc. This kind of flowmeter has intelligent protocol transmission, which can be connected with more intelligent devices to realize industrial On-site automation control. It is also possible to design some parameters of the intelligent electromagnetic flowmeter by the customer, so that the parameters of the flowmeter can better meet the requirements of the customer.

 

 

Intelligent electromagnetic flowmeter

Intelligent electromagnetic flowmeter features

 

1. Since the induced voltage signal is formed in the entire space filled with the magnetic field and is the average value on the pipe diameter surface, the straight pipe section required by the sensor is short and the pipe diameter is 5 times the length.

 

2. Intelligent electromagnetic flowmeter has various intelligent communication protocols, which can realize more settings on site and facilitate customers to configure products.

 

3. The sensor part only has the inner liner and the electrode in contact with the liquid to be tested. As long as the electrode and the inner lining material are properly selected, it can resist corrosion and wear.

 

4. The accuracy of the measurement of the intelligent circuit board is much higher than that of the previous analog signal transmission. Measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity. The sensor induced voltage signal is linear with the average flow rate, so measurement accuracy is high.

 

5. The LDE converter adopts the latest and most advanced single-chip microcomputer (MCU) and surface mount technology (SMT). It has reliable performance, high precision, low power consumption, stable zero point and convenient parameter setting. Click on the Chinese display LCD to display cumulative flow, instantaneous flow, flow rate, flow percentage, and more.

 

6, two-way measurement system, can measure forward flow, reverse flow. Special production processes and high-quality materials ensure that the performance of the product remains stable for a long time.


7. There is no obstruction in the measuring pipe, so there is no additional pressure loss; there is no moving parts in the measuring pipe, so the life of the sensor is extremely long.

Intelligent electromagnetic flowmeter

Intelligent electromagnetic flowmeter installation


The electromagnetic flowmeter works according to the principle of electromagnetic induction. Therefore, it should be away from the inverter, transformer, motor and other equipment that is prone to electromagnetic interference. The installation position should be protected from direct sunlight. The conductivity of the fluid to be tested should be substantially uniform. At the same time, we should also pay attention to the following aspects:

Upstream and downstream straight pipe sections

In order to achieve the same accuracy as the flow calibration for the flow meter used in the field, the specified flow conditions must be met. When the electromagnetic flowmeter is working, the upstream fluid is required to flow uniformly, and the disturbance of the downstream piping component does not affect the measured value, that is, a certain length of the upstream and downstream straight pipe sections is required. Generally, the length of the straight pipe section of the various flowmeters, elbows, and reducers of the flowmeter upstream of the electromagnetic flowmeter must be 5-10 D or more (D is the inner diameter of the flowmeter), and the length of the downstream straight pipe section should be 2~. 3D or more.

Liquid should be filled with pipes

The intelligent electromagnetic flowmeter can be installed horizontally, vertically or at any angle to the horizontal, but the piping structure must ensure that the measuring tube is always filled with liquid, otherwise an error will occur. When it has to be installed on a vertical pipe from top to bottom, the flow meter should be installed in the lower part of the pipe, and a throttle valve is installed downstream of the flow meter to generate a back pressure downstream.

No bubbles in the liquid

The piping should be designed to ensure that no air bubbles are separated from the liquid. Because the valve will act to change the pressure in the pipeline and create bubbles, the flowmeter should be installed upstream of the valve.

The electrode is parallel to the ground

When the electromagnetic flowmeter is installed horizontally or at an angle to the ground, the electrode wires are parallel to the ground. If the electrode wire is perpendicular to the ground, it is easy to collect bubbles in the vicinity of the previous electrode to block the liquid from contacting it, and the lower electrode is easily covered by the mud. Figure 1A is a schematic diagram of the DMA measurement principle. Figure 2 is a block diagram of the electromagnetic flowmeter.

Intelligent electromagnetic flowmeter

Liquid conductivity should be stable

Do not install the electromagnetic flowmeter where the fluid conductivity is extremely uneven. Especially in the case of chemical injection in the upstream of the meter, it is easy to cause unevenness of the conductivity, which has a serious impact on the meter indication. In this case, the chemical should be injected downstream of the meter. If it is to be injected upstream, the injection point should be kept at a certain distance from the flowmeter to make the liquid mix evenly.

Ground

Since the sensitive electromagnetic flowmeter has a small induced signal voltage and is susceptible to noise, the flowmeter must be well grounded. The electromagnetic flowmeter is equipped with a grounding ring, which functions to establish liquid grounding and protect the lining by contact with the liquid. Only in this way can the reference potential of the sensor and the reference potential of the converter/amplifier be the same as the measured liquid potential. It is also the same as the ground potential, reducing the effect of noise on the measurement results. It must be emphasized that the electromagnetic flowmeter must be grounded separately. Because if it is grounded together with other instruments or electrical devices, the leakage current in the grounding wire will cause serial-mode interference to the measurement signal. In severe cases, the flowmeter will not work. In addition, the grounding point should be away from large-scale electrical appliances to avoid ground currents flowing into the flowmeter, causing interference sources. In addition, during the installation process, it should also be noted that the electrode and rubber lining inside the flowmeter should not be damaged during welding (the electrode is usually two white metal points). When installing the flowmeter, a rubber gasket should be added between the flanges to Waterproof. Outdoor wiring should be avoided on rainy days.