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Electromagnetic flowmeter for measuring easy adhesion and precipitation fluid

Electromagnetic flowmeter measures how easy to attach and precipitate fluids: When measuring a fluid that is easy to adhere to and deposit substances on the pipe wall, if a conductive substance with a higher conductivity than the liquid is attached, the signal potential will be short-circuited and cannot work, if it is non-conductive The layer should first pay attention to the contamination of the electrode, such as the selection of the tip or hemispherical protruding electrode, the replaceable electrode, the scraper type cleaning electrode, etc. The scraper electrode can be manually scraped off the scale manually outside the sensor. Foreign products have been equipped with ultrasonic transducers on the electrodes to remove surface scale, but it is now rare. There is also a temporary disconnection of the measuring circuit, a low-voltage large current flows between the electrodes for a short period of time, and incineration removes the adhesion layer attached to the grease. Locations that are prone to adhesion can increase the flow rate for self-cleaning purposes, and can also be conveniently connected with easy-to-clean tubing without disassembling the cleaning sensor.
The non-contact electrode EMF is attached to the non-conductive film layer, and the meter can still work, but it is also inoperable if it is a highly conductive layer.
The additional indication error AE for the contact electrode EMF conductive adhesion layer is the adhesion layer and the liquid conductivity, respectively;
Adhesion layer thickness;
Measuring tube inner diameter.
If the foreign matter layer attached to the lining pipe wall is an oxidized rust layer or a dye containing a metal as a main component, the electrical conductivity is greater than the liquid conductivity, and the measured flow rate value is lower than the actual flow rate; if it is a scale layer such as calcium carbonate, The conductivity is lower than the liquid and the measured flow value will be higher than the actual flow. If the electrical conductivity of the adhesion layer is the same as that of the liquid, the additional error calculated by equation (8.3) is zero, but this is limited to the condition that the thickness of the adhesion layer is small, for example, as shown in Fig. 8.12, 2t/d is less than 10%. Because the flow rate decreases when the same flow rate has an adhesion layer, but the average flow rate increases, and can cancel each other, it can only be said that the additional error is negligible.

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