Can intelligent electromagnetic flowmeter measure mixed liquids?

　　1. Liquid containing bubbles

　　The electromagnetic flowmeter can still measure normally in the liquid mixed with tiny bubbles, but the measured volume flow is the mixed volume flow containing the bubble volume. If the gas content increases to form a block flow, the electrode may be covered by the gas, causing the circuit to be disconnected instantly, resulting in output shaking or even failure to work normally.

　　2. Liquid in solid-liquid two-phase flow

　　Solid-liquid two-phase fluids containing non-ferromagnetic particles or fibers can also measure the volume flow of the two phases. Fluids with high solid content, such as drilling mud, drilling cementing slurry, pulp, etc. Since the solids flow together in the carrier liquid, there is sliding between the two and there is a difference in speed, the electromagnetic flowmeter for single-phase liquid inspection will produce additional errors when used for solid-liquid two-phase fluids.

　　If there are larger particles in the slurry that rub against the electrode surface, spike-like slurry noise will be generated in the electromagnetic flowmeter with lower frequency rectangular excitation, making the flow signal unstable. In this case, it is necessary to select a higher frequency instrument or a flowmeter with stronger slurry noise suppression capability.

　　3. Liquids containing ferromagnetic substances

　　Fluids containing ferromagnetic substances will cause measurement errors for common intelligent electromagnetic flowmeters because the magnetic permeability in the measuring tube changes due to the different contents of ferromagnetic substances. However, electromagnetic flowmeters with external compensation EMF with flux detection coils in the magnetic circuit can reduce the impact of mixed ferromagnetic substances. The test report shows that for ore slurry containing iron ore with a liquid-solid weight ratio of about 4:1 and a particle size of ≤0.15mm, a flow test of clean water and slurry was conducted with an 80mm diameter meter. The indication value of the common meter changed by 7%-10%, while the indication error of the meter equipped with flux detection coils was within ±2%Fs.

　　4. Slurry

　　When used to measure slurry containing ore particles, attention should be paid to the degree of wear on the sensor lining. The expansion of the inner diameter of the measuring tube will produce additional errors. In this case, ceramic linings or polyurethane rubber linings with better wear resistance should be selected. At the same time, it is recommended that the sensor be installed on a vertical pipe to make the pipe wear evenly and eliminate the disadvantage of severe local wear in the lower half of the horizontal installation.

　　In summary, intelligent electromagnetic flowmeters can be used to measure mixtures, and good measurement results can also be obtained as long as relevant adverse factors are avoided.