Advantages and disadvantages analysis of electromagnetic flowmeter

Electromagnetic flowmeter is a new type of flow measuring instrument developed rapidly with the development of electronic technology in the 1960s. It is made according to Faraday's law of electromagnetic induction and measures the flow of conductive fluid according to the electromotive force induced when the conductive fluid passes through an external magnetic field. . At present, it has been widely used in the measurement of various conductive liquids in industry. For example, measuring various acids, alkalis, salts and other corrosive liquids; various flammable and explosive media; various industrial sewage, pulp, mud, etc. The advantages of electromagnetic flowmeter: 1. The transmitter has a simple structure, no moving parts, and no throttling parts that hinder the flow of fluid, so when the fluid passes through, it will not cause any additional pressure loss, and it will not cause such as Wear, clogging and other problems, especially suitable for measuring slurry with solid particles, liquid-solid two-phase fluids such as sewage, and various viscous slurries. 2. The electromagnetic flowmeter is a volume flow measuring instrument, which is not affected by the temperature of the measured medium during the measurement process. Effects of viscosity, density, and (within certain limits) conductivity. Therefore, the electromagnetic flowmeter can be used to measure the flow of other conductive liquids only after being calibrated with water without additional corrections. 3. No mechanical inertia, sensitive response, can measure instantaneous pulsating flow, and good linearity. Therefore, the measurement signal can be linearly converted into a standard signal output by the converter, which can be indicated locally or transmitted over a long distance. 4. The range is extremely wide, and the range ratio of the same electromagnetic flowmeter can reach 1:100. In addition, the electromagnetic flowmeter is only proportional to the average flow velocity of the measured medium, and has nothing to do with the flow state (laminar flow or turbulent flow) under the axisymmetric distribution. Disadvantages of electromagnetic flowmeter: 1. It cannot be used to measure gas, vapor and liquid containing a large amount of gas. 2. Due to the temperature limitation of the insulating lining material of the measuring tube, the current industrial electromagnetic flowmeter cannot measure high temperature and high pressure fluid. 3. Affected by the flow velocity distribution, the flow signal is proportional to the average flow velocity under the condition of axisymmetric distribution. Therefore, the electromagnetic flowmeter also has a certain length of front and rear straight pipe sections. 4. Vulnerable to external electromagnetic interference. 5. At present, it cannot be used to measure the liquid medium with very low conductivity. The conductivity of the measured liquid medium should not be lower than 10-5 (S/cm), which is equivalent to the conductivity of distilled water. It can't do anything about petroleum products or organic solvents.