The importance of installing and using electromagnetic flowmeters

Correct installation of electromagnetic flowmeter is extremely important for the normal operation of electromagnetic flowmeter. The following China Sensor Trading Network will introduce you to the issues that should be paid attention to when installing and using electromagnetic flowmeter sensors and converters:
       (1) Installation location. The shell protection level of ordinary electromagnetic flow sensor is IP65.
       1) When measuring mixed phase fluid, a place that will not cause phase separation should be selected. 
       2) Select a place where there will be no negative pressure in the measuring duct. 
       3) It should be installed in an environment without strong electric field. There should be no large electrical equipment nearby. The requirements for the installation location are such as motors, transformers , etc. to avoid interference from electric field. 
       4) Avoid installation in places with strong corrosive gases around  .
       5) The ambient temperature should generally be within the range of -25-60℃, and avoid direct sunlight as much as possible. 
       6) Install in a place with no vibration or low vibration. If the vibration is too large, the pipes before and after the sensor should be fixed with support. 
       7) The relative humidity of the environment should generally be within the range of 10%.-90%. 
       8) Avoid installing in places where it can be directly exposed to rain or immersed in water. If the protection level of the sensor shell is IP67 or IP68 (dust and water proof), the last two items are not required.
       (2) Straight pipe length. The electromagnetic flowmeter has relatively low requirements for the length of the straight pipe section before the meter. Generally, for flow resistance parts such as 90" elbows, T-shaped tees, reducers, and fully open doors, there should be a straight pipe section length of 3-5D from the center line of the sensor electrode axis (not the sensor inlet end face); for valves with different openings, a straight pipe section length of 10D is required; there should generally be a straight arm section length of 2D behind the sensor. When the valve can be fully opened, if the valve cutoff direction is installed at 450 with the sensor electrode axis, the additional error can be greatly reduced;
       (3) Installation position and flow direction. The electromagnetic flowmeter can be installed horizontally, vertically or obliquely. This can not only prevent the short-term insulation of the electrode caused by the bubbles entrained by the fluid, but also prevent the electrode from being covered by the sediment in the fluid. The flowmeter should not be installed at the highest point to avoid gas accumulation. The electromagnetic flowmeter used is installed at the highest point in the pipeline, which is a bad installation position and should be avoided. When installed vertically, the fluid should flow through the electromagnetic flowmeter from bottom to top. In this way, when there is no flow or the flow is very small, the heavier solid particles entrained in the fluid will sink, while the lighter fat substances will rise and leave the sensor electrode area. When measuring liquid-solid two-phase flows such as mud and slurry, vertical installation can avoid solid phase precipitation and uneven wear of the sensor insulation lining. The
       installation place of the electromagnetic flowmeter should have a certain back pressure. Direct emptying of the flowmeter outlet is likely to cause the liquid in the measuring tube to be not full. This is a bad installation position and should be avoided. In order to prevent negative pressure from being generated in the electromagnetic flow juice, the electromagnetic flowmeter should be installed behind the pump;
       (4) Install a bypass pipe. The measurement accuracy of the electromagnetic flowmeter is affected by the scale on the inner wall of the measuring tube, especially near the electrode. During use, attention should be paid to maintenance and cleaning. In order to facilitate maintenance and zero point adjustment, bypass pipes should be installed as much as possible for small and medium diameter pipes so that the electromagnetic flowmeter is filled with stagnant measured liquid.
       (5) Correct grounding. The signal of the electromagnetic flowmeter is relatively weak, with only a few millivolts at full scale and only a few microvolts when the flow rate is very small. Any slight interference from the outside will affect the measurement accuracy. Therefore, the electromagnetic flow sensor must be grounded separately, and its "ground" should be connected to the "ground" of the measured liquid and the converter with a wire, and then buried deep underground with a grounding wire; the grounding resistance should be small, and there should be no ground current at the grounding point. Ensure good grounding and good point contact between the fluid, shell, and pipeline. Never connect it to the motor or upstream and downstream pipelines.
       (6) The signal line should be inserted into the grounded steel pipe separately, and it is not allowed to be inserted into the same steel pipe as the power line. The signal line must be shielded and the length must not exceed 30m. If the signal line needs to be extended, certain measures must be taken, such as using double-shielded cables, shielded drivers, etc.
       (7) The flow direction of the measured liquid should be the direction specified by the transmitter, otherwise the flow signal will be phase-shifted by 180°, the phase-sensitive detector cannot detect the flow signal, and the instrument will have no output.