For any magnetic flowmeter (magmeter) system to function properly it must have three connections (including a ground) to the process liquid passed from the magmeter flowtube onto the magmeter flow transmitter. About 80 percent of the time, problems with the flow measurement readings provided by a magmeter can be traced directly to improper solution ground connections.
The function of the electromagnetic flow meter grounding ring: the grounding ring directly contacts the medium through the grounding electrode, and then grounds the grounding ring and the flange of the electromagnetic flow meter to reach the ground potential to eliminate interference.
The use-method of grounding ring of the electromagnetic flow meter: in some occasions, it is not suitable to increase the grounding ring. For example, when measuring strong corrosive medium, the pipe will be made of PVC or PTFE-plated electrode, which is precious metal, especially for large diameter. Say, it is impossible to match the grounding ring, and the cost is too high. In this case, three electrodes are generally selected, two of which are for measurement and the other for grounding.
Generally, if the pipe is made of metal or not with a grounding ring, the flange of the flow meter and the pipe are connected and then grounded, which can also be used well, especially in the case of large diameter. If you have a small diameter, it doesn’t matter if you have a grounding ring, and the cost will not be too much. In addition, some users do not measure strong corrosive media, but the pipeline is non-metallic. At this time, it must be equipped with a grounding ring. Grounding is very important for electromagnetic flow meters. The interference of the field magnetic field is fatal to the electromagnetic, because the electric field can be shielded by some means, but the magnetic field can’t be shielded, so the electromagnetic flow meter must be installed to avoid the strong magnetic field.
Because the signal is weak, only 2.5~8mv at full scale, only a few microvolts when the flow rate is very small, the external interference will affect the measurement accuracy. Therefore, the convertor casing, shielded wire, measuring conduit and transmission should be grounded, and the grounding point should be set separately. It
must not be connected to the common ground wire or the upper and lower water pipes of the motor and electrical appliances. The converter part has been grounded through the cable, so do not ground again to avoid interference caused by different ground potentials.
