At present, electromagnetic flowmeter has advantages over other types of flowmeter in terms of reliability and stability and is widely used in sewage treatment, municipal and industrial water supply, the petrochemical industry, medicine, steel, and many other aspects. However, in the measurement of electromagnetic flowmeter, there is one point to note: the liquid medium is not required to have conductive liquid, and some problems will occur in the actual use process of users.
This article gives a detailed description of the selection and installation of an electromagnetic flowmeter.To guide users to correctly install and use the electromagnetic flowmeter. In the process of use, some conditions may occur more or less due to operational negligence and non-compliance with the specification, which requires the operator to read the product instruction manual before installation carefully. In accordance with the requirements of the specification, and at the same time pay attention to selecting the correct installation position, the efficiency of the electromagnetic flowmeter can be well played, and the stability of its operation can be effectively guaranteed, Ensure the accuracy and service life of the measured data.
The electromagnetic flowmeter sensor shall be installed indoors in a dry and ventilated place. Avoid installing in places with high ambient temperature and strong vibration, and try to avoid equipment with strong magnetic fields, such as large motors, transformers, etc. Avoid installation in places with corrosive gas. The installation site is convenient for maintenance. This is the environmental condition to ensure the regular operation of the sensor. To ensure that the measuring pipe of the sensor is full of the measured medium, the transmitter is installed vertically and flows from bottom to top. Especially for liquid-solid two-phase, it must be installed vertically. If only horizontal installation is allowed on site, the two electrodes must be at the same level.
A few millivolts of AC potential measured by the electrode of the electromagnetic flow sensor are based on the potential inside the sensor. In order to stabilize the liquid potential and maintain the equipotential between the sensor and the fluid to ensure stable measurement, the sensor shell and both ends of the metal tube should be well grounded, and the converter shell should also be dropped. The grounding resistance shall not be greater than 10 Ω and shall not be shared with the grounding wires of other electrical equipment. If good contact between the sensor housing and the metal pipe cannot be guaranteed, they shall be connected with metal wires.
And then reliably grounded. Grounding In order to ensure accurate measurement and no current corrosion of the electrode, the electromagnetic flow sensor must be grounded separately, and the sensor and the fluid must be at approximately the same potential. In principle, the separate electromagnetic flowmeter shall be leveled at the sensor side, and the converter shall be dropped at the same grounding point. In most cases, the internal reference electrode or metal tube of the sensor can ensure the allowable potential balance. Therefore, the fluid in the tube can be grounded through the built-in reference electrode and metal tube, and the grounding lug of the sensor can be connected with the grounding wire.In order to avoid the influence of the flow rate on the measurement, the flow regulating valve should be set downstream of the transmitter For small caliber transmitters, since the distance from the electrode center to the inlet end of the flowmeter is several times the length of diameter D, the upstream straight pipe may not be specified, however, for the flowmeter with large diameter, generally there should be a straight pipe section of more than 5D in the upstream, and generally, there is no straight pipe section requirement in the downstream.