Tungsten carbide electromagnetic flowmeter electrode cleaning the correct key points

As an intelligent and precise pipe flow measurement instrument, the tungsten carbide electromagnetic flowmeter has many advantages that other types of flow instruments do not have, such as not being affected by changes in fluid density, viscosity, temperature, pressure and conductivity; There are only flowing parts in the measurement tube, no pressure loss, and low requirements for straight pipe sections; there are many choices for sensor lining and electrode materials; the converter adopts a novel excitation method, which has low power consumption, stable zero point, and high accuracy. Therefore, it has been widely used in industrial production. At the same time, for various measurement media and different measurement working conditions, electromagnetic flowmeter types that adapt to different media and different environments have emerged, such as battery-powered, anti-corrosion, etc. Type, submersible electromagnetic flowmeter. If the medium measured by the tungsten carbide electromagnetic flowmeter is relatively dirty for a long time, scaling will occur on the electrodes after the electromagnetic flowmeter has been working for a period of time. When the conductivity of the scaling material is different from the conductivity of the measured medium, measurement errors will occur.

The attachment of sludge and oil to the electrode will also cause the instrument output to swing and drift. Therefore, in this case, we need to regularly maintain and clean the electromagnetic flowmeter electrodes. 1. For inorganic pollution, the electrode can be immersed in 0.1mol/L dilute hydrochloric acid for 30 minutes, washed with pure water, and then immersed in 3.5MOL/L potassium chloride solution for 6 hours before use. 2. Soak in 4% hydrogen fluoride solution for 3 to 5 seconds, take out and rinse with distilled water, then soak in 0.1mol/L hydrochloric acid solution for several hours, rinse with distilled water, and calibrate. 3. If the platinum surface is seriously polluted and an oxide film is formed, you can use toothpaste to polish the platinum or gold surface, then clean it with pure water, and then immerse it in 3.5MOL/L potassium chloride solution for 6 hours before use. 4. For organic oil stains and oil film pollution, you can use detergent to clean the platinum or gold surface, then rinse it with pure water, and then immerse it in 3.5MOL/L potassium chloride solution for 6 hours before use.

Five tests of tungsten carbide electromagnetic flowmeter 1. Electrode contact resistance. Measuring the liquid contact resistance value of the electrode scoop can indirectly evaluate the general condition of the electrode and lining surface without removing the flow sensor from the pipeline, which is helpful to analyze the cause of the failure. 2. The polarization voltage of the electrode. Measuring the polarization voltage between the electrode and the liquid will help determine whether the unstable zero point or output shaking failure is caused by the electrode being contaminated or covered. Use the 2V DC range of a digital multimeter to measure the polarization voltage between the two electrodes and the ground (the electromagnetic flowmeter can be measured without power outage or without power outage). If the two measurements are nearly equal, the electrode is not contaminated or covered. The size of the polarization voltage depends on the "electrode potential" of the electrode material and the properties of the liquid. The measured value may range from a few mV to hundreds of mV. Because in fact, the contamination conditions of the two electrodes during operation cannot be the same and symmetrical, so the voltages on the two electrodes form an asymmetric common mode voltage. The asymmetric common-mode voltage becomes a differential-mode signal, causing a zero offset. 3. Identification of pipeline stray current flow direction. Sometimes, in order to find whether the source of stray interference in the pipeline is upstream or downstream of the flow sensor,To narrow the search scope and try to reduce or eliminate the influence of stray current interference. 4. Determination of signal cable interference. The signal cable is interfered by external electrostatic induction and electromagnetic induction, which will cause the zero point of the electromagnetic flowmeter to change. In order to determine whether the zero point change is due to the interference potential of the signal cable, it is necessary to determine the general scope of the interference and the degree of impact on the electromagnetic flowmeter. 5. Determine whether there is ground potential. During normal use of the electromagnetic flowmeter, if the motor (force) state near the sensor changes (such as leakage), the ground potential will change, causing the zero point to change. To check whether this is affected, you can short-circuit the converter's working ground C terminal and protective ground G terminal, and use the zero point (or indicated value) change to determine whether there is a ground potential.