5/3/2024 0 Comments Sewer flow meterIn typical applications, magnetic flowmeters are sized so that the velocity at maximum flow is approximately 2-3 meters per second. Provide an allowance for changing composition and operating conditions that can change the electrical conductivity of the liquid. Application Cautions for Magnetic Flowmetersĭo not operate a magnetic flowmeter near its electrical conductivity limit because the flowmeter can turn off. In order of usage, water/wastewater industry, chemical, food and beverage, oil and gas (although not for oil and gas fluids but in support of the processes), power, pulp and paper, metals and mining, and pharmaceutical. Similarly, excessive temperature in magnetic flowmeters (even briefly under abnormal conditions) can result in permanent flowmeter damage. Note that vacuum conditions can occur in pipes that seemingly are not exposed to vacuum service such as pipes in which a gas can condense (often under abnormal conditions). Failure to ensure that the flowmeter is completely filled with liquid can significantly affect the flow measurement.īe especially careful when operating magnetic flowmeters in vacuum service because some magnetic flowmeter liners can collapse and be sucked into the pipeline in vacuum service, catastrophically damaging the flowmeter. Be sure that the orientation of the flowmeter is such that the flowmeter is completely filled with liquid. ![]() ![]() Magnetic flowmeters are often used where the liquid is fed using gravity. Slurry applications are commonly found in the mining, mineral processing, pulp and paper, and wastewater industries. Corrosive liquid applications are commonly found in the chemical industry processes, and in chemical feed systems used in most industries. With proper attention to materials of construction, the flow of highly corrosive liquids (such as acid and caustic) and abrasive slurries can be measured. Mining and mineral process industry applications include process water and process slurry flows and heavy media flows. Magnetic flowmeters are used in water treatment plants to measure treated and untreated sewage, process water, water and chemicals. Water and wastewater applications include custody transfer of liquids in force mains between water/wastewater districts. ![]() Magnetic flowmeters typically require 3-5 diameters of upstream straight run and 0-3 diameters of downstream straight run measured from the plane of the magnetic flowmeter electrodes.Īpplications for dirty liquids are found in the water, wastewater, mining, mineral processing, power, pulp and paper, and chemical industries. Magnetic flowmeters do not require much upstream and downstream straight run so they can be installed in relatively short meter runs. Magnetic flowmeters can be applied to the flow of liquids that are conductive, so hydrocarbons and gases cannot be measured with this technology due to their non-conductive nature and gaseous state, respectively. This flowmeter does not obstruct flow, so it can be applied to clean, sanitary, dirty, corrosive and abrasive liquids. Be careful because using magnetic flowmeters on fluids with low conductivity, such as deionized water, boiler feed water, or hydrocarbons, can cause the flowmeter to turn off and measure zero flow. Magnetic flowmeters can measure properly when the electrical conductivity of the liquid is greater than approximately 5μS/cm. Magnetic flowmeters measure the velocity of conductive liquids in pipes, such as water, acids, caustic, and slurries. On the other hand, don’t work on nonconductive fluids such as oils. Mags are intermediate in accuracy therefore not commonly used for commodity transfer except for some special cases where the fluid is not expensive like water. ![]() They represent about 23% of all flowmeters sold. As such, the turndown associated with magnetic flowmeters can approach 20:1 or better without sacrificing accuracy. In contrast with many other flowmeter technologies, magnetic flowmeter technology produces signals that are linear with flow. The electronic transmitter processes the voltage signal to determine liquid flow. Faraday’s Law states that the voltage generated is proportional to the movement of the flowing liquid. When the fluid moves faster, more voltage is generated. Following Faraday’s Law, flow of a conductive liquid through the magnetic field will cause a voltage signal to be sensed by electrodes located on the flow tube walls. In a magnetic flowmeter, a magnetic field is generated and channeled into the liquid flowing through the pipe. Magnetic flowmeters use Faraday’s Law of Electromagnetic Induction to determine the flow of liquid in a pipe. They can handle light particulate, have a higher pressure drop, lower rangeability and are slightly less accurate. A less expensive alternative to Magnetic technology: CoolPoint vortex shedders.
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