How to better meet the installation requirements for electromagnetic flowmeters

Thread Content

An electromagnetic flowmeter is a flowmeter that measures flow based on Faraday’s law of electromagnetic induction. The advantages of electromagnetic flowmeters are extremely low pressure loss and a wide measurable flow range. The ratio of the maximum flow rate to the minimum flow rate is generally above 20:1. It is suitable for a wide range of industrial pipe diameters, up to 3 meters. The output signal is linear with respect to the measured flow rate, ensuring high accuracy. It can be used to measure the flow rate of fluids such as acids, bases, salt solutions, water, wastewater, corrosive liquids, as well as sludge, pulp, and paper pulp, provided their conductivity is ≥5μs/cm. But it cannot measure the flow rate of gases, vapors, and pure water. Due to the various advantages of electromagnetic flowmeters, more companies are now using them. So, how should electromagnetic flowmeters be installed? What installation requirements are necessary to ensure better performance, greater accuracy, and improved safety? The installation of electromagnetic flowmeters is very important (we have discussed this in previous articles; more information can be found on the Chengfeng Instruments website). In fact, determining how to properly ground the electromagnetic flowmeter during installation is also a crucial issue. To this end, when installing electromagnetic flowmeters, we should pay attention to the following points: 1) The grounding terminals of the sensor and converter must be at the same potential as the medium being measured. 2) Using the ground as a zero potential point to reduce external interference. Since ordinary process pipelines are made of metal and are grounded by default, this requirement is relatively easy to meet. However, if there is significant external electromagnetic interference, then the grounding setup needs to be adjusted again; multi-strand copper wires with a cross-sectional area of more than 5 mm2 should be used for the grounding wires, and they must not be connected to the motor or the common ground wire in order to avoid interference from leakage currents. 3) The sensor is installed on metal pipes (which do not have an insulating coating on their inner walls). 4) When installed on plastic pipes or pipes with an insulating lining, grounding rings, grounding flanges, or short tubes equipped with grounding electrodes must be installed at both ends of the sensor. 5) The fluid flowing in the pipeline is in short circuit with the ground, resulting in a zero potential; otherwise, the electromagnetic flowmeter cannot function properly.