Electromagnetic Flowmeter

The measurement principle of the electromagnetic flowmeter is an instrument that measures the flow of conductive fluid based on Faraday's law of electromagnetic induction based on the electromotive force induced when the conductive fluid passes through an external magnetic field. The main components of the sensor are the measuring tube electrode excitation coil core and the yoke shell. The product is mainly used to measure the volume flow of conductive liquids and slurries in closed pipelines, including highly corrosive liquids such as acids, alkalis, and salts. Electromagnetic flowmeters are widely used in petrochemical, metallurgical, textile, food, pharmaceutical, paper and other industries as well as environmental protection, municipal management, water conservancy construction and other fields. Product Features of Electromagnetic Flowmeter
Measurement is not affected by changes in fluid density, viscosity, temperature, pressure and conductivity
There are lower requirements for straight pipe sections with no obstruction to flow parts and no pressure loss in the measurement tube. It has unique adaptability to slurry measurement
Series nominal diameter ~. There are many choices for sensor lining and electrode materials
The converter adopts a novel excitation method with low power consumption, zero point stability and high accuracy. The flow range can be reached
The converter can be integrated with the sensor or separate type
The converter uses a high-performance microprocessor to display parameter settings, easy to program and reliable
The electromagnetic flowmeter is a bidirectional measurement. The system is equipped with three totalizers, forward total, reverse total and difference total, which can display the reverse flow and have a variety of output current pulse digital communications
The converter adopts surface mounting technology and has self-test and self-diagnosis. Function
Structural composition of electromagnetic flowmeter
The function of the magnetic circuit system is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented with permanent magnets. Its advantage is that the structure is relatively simple and is less disturbed by the AC magnetic field. However, it is easy to polarize the electrolyte liquid in the measuring catheter, so that the positive electrode is surrounded by negative ions, and the negative electrode is surrounded by positive ions, that is, the pole of the electrode. chemical phenomenon and causes the internal resistance between the two electrodes to increase, thus seriously affecting the normal operation of the instrument. When the diameter of the pipe is large, the permanent magnet is correspondingly large, bulky and uneconomical. Therefore, electromagnetic flowmeters generally use alternating magnetic fields and are generated by power frequency power supply.
The function of the measuring catheter is to allow the conductive liquid to be measured to pass through. In order to cause the magnetic flux to be shunted or short-circuited when the magnetic lines of force pass through the measuring conduit, the measuring conduit must be made of materials that are non-magnetic, have low electrical conductivity, low thermal conductivity and a certain mechanical strength. Non-magnetic stainless steel, glass fiber reinforced plastic, high-strength plastic aluminum, etc. can be used.
The function of the electrode is to elicit an induced potential signal that is proportional to the measured value. The electrodes are generally made of non-magnetic stainless steel and are required to be flush with the lining so that fluid can pass through unimpeded. Its installation position should be in the vertical direction of the pipe to prevent sediment from accumulating on it and affecting the measurement accuracy.
The outer shell should be made of ferromagnetic material to cover the excitation coil of the distribution system and isolate the interference of the external magnetic field.
Lining There is a complete electrically insulating lining on the inside of the measuring tube and on the flange sealing surface. It directly contacts the measured liquid and its function is to increase the corrosion resistance of the measuring tube and prevent the induced potential from being short-circuited by the metal measuring tube wall. The lining materials are mostly corrosion-resistant, high-temperature and wear-resistant polytetrafluoroethylene plastic ceramics.
The induced potential signal generated by the converter due to liquid flow is very weak and is greatly affected by various interference factors. The function of the converter is to amplify and convert the induced potential signal into a unified standard signal and suppress the main interference signals. Its task is to amplify and convert the induced potential signal detected by the electrode into a unified standard DC signal.