After years of development, electromagnetic flowmeters have continuously improved their performance and gradually become more powerful. There are also various types according to the classification, such as DC excitation type, AC power frequency excitation type, dual frequency excitation type and low frequency rectangular wave excitation type according to the excitation method. They are all based on the principle of Faraday's law of electromagnetic induction, a kind of instrument for measuring the volume flow of conductive liquid. Electromagnetic flowmeters have minimal pressure loss, no requirements for media density, viscosity, temperature, pressure and other parameters, and the requirements for straight pipe sections are also very low. Here's a summary of how to choose a flowmeter. 1. The conductivity of the medium The conductivity of the medium cannot be lower than the specified lower limit value. If it is lower than the lower limit value, a measurement error will occur, resulting in abnormal use. Even if the upper limit value is changed, it can be measured, and the indication error does not change much. The conductivity of industrial water and its aqueous solution is greater than 10-4S / cm, the conductivity of acid, alkali, salt solution is between 10-4 ~ 10-1S / cm, and the low-degree distilled water is 10-5S / cm. There is no problem, such as petroleum products and organic solvents with too low conductivity can not be used. The aqueous solution used may be proportioned with industrial water, the conductivity will be slightly higher, which is conducive to flow measurement. The figure below lists the conductivity of several liquids at 20 ° C. 2. Electrode material In order to achieve a good measurement effect and a longer service life in the measurement process, the electrode material must be selected according to whether the fluid being tested is corrosive. For details, please consult the manufacturer's corrosion manual. The following figure shows common electrode materials and corresponding corrosion resistance. 3. Range caliber The caliber of the sensor does not have to be the same as the pipe diameter, it must be determined according to the actual flow, and the caliber of the flowmeter is selected according to the calculation formula. For industrial transportation of water and other liquids, the general pipeline flow rate is 1.5 ~ 3m / s. The electromagnetic flowmeter is used on such a pipeline. The sensor caliber is the same as the pipe diameter. When the electromagnetic flowmeter is at full flow rate, the liquid flow rate can be selected within the range of 1 ~ 10m / s. The upper limit flow rate is not limited in principle, it is recommended not to exceed 5m / s, if the lining material can withstand liquid flow erosion. The lower limit of the flow rate of full-scale flow is generally 1m / s, and some models are 0.5m / s. For fluids with easy adhesion, deposition, scaling, etc., the flow rate is not less than 2m / s, preferably increased to 3 ~ 4m / s or more, which plays the role of self-cleaning and prevention of adhesion and deposition. For abrasive fluids such as ore pulp, the common flow rate should be less than 2 ~ 3m / s to reduce the wear on the lining and electrodes. When measuring low-conductivity liquids close to the threshold, select a lower flow rate (less than 0.5 ~ 1m / s) as much as possible. The flow noise will increase due to the increase of the flow rate, and the output will sway. 4. Contains mixture The tiny bubbles mixed into the bubble flow can still work normally, but the measured mixed volume flow rate containing the bubble volume, the gas content increases to form a bullet (block) flow, the electrode may be covered by the gas and the circuit is momentarily disconnected. The output swaying may not even work properly. 5. There is precipitation in the medium When the liquid is easy to adhere to the fluid of the pipe wall and precipitate substances, if a conductive substance with a higher conductivity than the liquid is attached, the signal potential will be short-circuited and cannot work. Attach pointed or hemispherical protruding electrodes, replaceable electrodes, scraper-type cleaning electrodes, etc. The place where adhesion is easy can increase the flow rate to achieve the purpose of self-cleaning, and it can also take a more convenient and easy-to-clean pipe connection without disassembling the cleaning sensor. The contact type electrode electromagnetic flowmeter is attached with a non-conductive film layer, and the instrument can still work, but if it is a highly conductive layer, it cannot work. As an important industrial flow measurement instrument, electromagnetic flowmeter fully exerts its role in application. How to select and install it has become a key issue. Under the premise of having certain professional knowledge, it is necessary to master certain skills and methods in how to correctly select and install them, in order to meet the requirements of in-depth management of enterprises and the requirements of vortex flowmeters.
biodegradable and compostable shopping bag
Extra thick&leak proof
Break down in 90 days
Easy dispensing box
100% Biodegradable Shopping Bag Biodegradable Shopping Bag,Biodegradable Grocery Bags,Biodegradable Shopping Bags Wholesale ,Biodegradable Plastic Bags Wholesale DongGuan Sengtor Plastics Products Co., Ltd. , https://www.sentebio.com
Share the main points of knowledge of electromagnetic flowmeter selection