Electromagnetic flowmeter in the installation and use of the process there will be some problems, leading to measurement problems, most of the reason is that the flowmeter in the installation and commissioning problems, these are the key factors of failure.
1. On the upstream side of the flow meter, if there are valves, elbows, three-way pumps and other spoilers, the front straight pipe section should be greater than 20DN
2, the installation of electromagnetic flowmeter, especially the polytetrafluoroethylene lining material flow timing, the bolts connecting the two flanges should pay attention to uniform tightening, otherwise it is easy to crush the polytetrafluoroethylene lining, with a torque wrench.
3, when the pipeline stray current interference, space electromagnetic wave or large motor magnetic field interference. Stray current interference in pipelines is usually measured satisfactorily with good individual ground protection. However, if the pipeline has strong stray current can not be overcome, it is necessary to take measures to insulate the flow sensor and the pipeline. Space electromagnetic wave interference is generally introduced by signal cable, which is usually protected by single layer shielding.
4, usually electromagnetic flow meters also have protection level requirements, usually integrated protection level is IP65, split type is IP68, if the customer has requirements for the instrument installation environment, installation site in underground Wells or other wet places, it is recommended that customers choose split type.
5, in order to avoid interfering with the signal, the signal between the transmitter and the converter must be transmitted with a shielded wire, the signal cable and the power line are not allowed to be placed parallel in the same cable steel pipe, the signal cable length generally shall not exceed 30m.
6, in order to ensure that the electromagnetic flow transmitter measuring tube is filled with the measured medium, it is recommended to install vertically, flow from bottom to bottom, especially for liquid-solid two-phase flow, must be installed vertically. If only horizontal installation is allowed on site, ensure that the two electrodes are in the same horizontal plane.
7, if the measured liquid carries particles, such as measuring sludge, sewage, etc., the electromagnetic flowmeter must be installed vertically, and keep the flow from bottom to bottom, to ensure that the electromagnetic flowmeter is always full tube, but also can effectively reduce the appearance of bubbles.
8. The flow rate of the electromagnetic flowmeter is within the range of 0.3 ~ 12m/s, and the diameter of the flowmeter is the same as that of the process pipe. If the flow rate in the pipeline is low, it can not meet the requirements of the flowmeter for the flow rate range, or the measurement accuracy is not high in this flow rate, try to increase the flow rate locally in the instrument part, and adopt the shrink tube type.
9, electromagnetic flowmeter can be installed in a straight pipe, can also be installed on a horizontal or inclined pipe, but requires the center line of the two electrodes to be in a horizontal state.
10, electromagnetic flowmeter in the subsequent use of the process to regularly clean the instrument, regularly check the problem of the flowmeter:
(1) Electromagnetic flowmeter sensor electrode wear, corrosion, leakage, scaling. Especially for precipitated, easily contaminated electrodes, containing solid phase of the non-clean liquid;
(2) excitation coil insulation decline;
(3) The insulation of the converter decreases;
(4) Converter circuit failure;
(5) The connection cable is damaged, short-circuited, and damp;
(6) New changes in instrument operating conditions are not excluded.
Post time: Dec-04-2023