Electromagnetic flowmeter component introduction

Case introduction

It consists of two parts: sensor and converter. It works based on Faraday's law of electromagnetic induction and is used to measure the volume flow of conductive liquids with a conductivity greater than 5 μS/cm. It is an inductive instrument that measures the volume flow of conductive media. In addition to measuring the volume flow of general conductive liquids, it can also be used to measure the volume flow of highly corrosive liquids such as strong acids and alkalis, and uniform liquid-solid two-phase suspension liquids such as mud, pulp, and paper pulp. It is widely used in flow measurement in petroleum, chemical industry, metallurgy, textile, papermaking, environmental protection, food and other industrial sectors and municipal management, water conservancy construction, river dredging and other fields. Electromagnetic flowmeter magnetic circuit system: its function is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented with magnets. Its advantage is that the structure is relatively simple and is less disturbed by the AC magnetic field. However, it easily polarizes the electrolyte liquid passing through the measurement catheter, causing the positive electrode to be surrounded by negative ions and the negative electrode to be surrounded by positive ions. , that is, the polarization phenomenon of the electrodes, 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 magnet is correspondingly large, bulky and uneconomical. Therefore, electromagnetic flowmeters generally use alternating magnetic fields and are generated by 50HZ power frequency power supply.

Electromagnetic flowmeter measuring conduit: Its function 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 field lines 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 have a certain mechanical strength. Non-magnetic stainless steel, glass fiber reinforced plastics, and high-strength materials can be used. Plastic, aluminum, etc.

Electromagnetic flowmeter electrode: Its function 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.

Electromagnetic flowmeter housing: Made of ferromagnetic material, it is the outer cover of the distribution system excitation coil and isolates the interference of the external magnetic field.

Electromagnetic flowmeter lining: There is a complete electrical insulation lining on the inside of the measuring conduit 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. Lining materials are mostly corrosion-resistant, high-temperature-resistant, wear-resistant polytetrafluoroethylene plastics, ceramics, etc.

Electromagnetic flowmeter converter: The induced potential signal generated by the 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 interfering signals. Its task is to amplify and convert the induced potential signal Ex detected by the electrode into a unified standard DC signal.