Various factors, such as use, directly affect the measurement of electromagnetic flowmeter.
The effect of medium temperature electromagnetic flowmeter measuring tube is generally made of non-conducting high resistance materials (such as stainless steel), at the same time, in the measurement of the inner wall of the conduit and the electrode is equipped with an insulating lining between the two electrodes is to prevent the two electrodes by the short-circuiting of the metal conduit, and secondly, to prevent the conduit from being corroded, and to make the inner wall smooth. Lining materials depending on the operating temperature is different, electromagnetic flowmeter, using PTFE lining, the operating temperature up to 177 ℃. If the measurement of the medium temperature for a long time over this temperature, will lead to the lining material of the measuring tube expansion, deformation and quality change, resulting in damage to the flow tube. Therefore, before the start of the device, the process personnel with steam to blow the pipeline, if not beforehand to remove the flowmeter on the pipeline, it is also easy to cause damage to the flowmeter.
The impact of environmental temperature if the use of electromagnetic flowmeter is mostly used to measure the flow of mixtures containing solid particles and slurry, in order to ensure that the slurry does not solidify, not only the pipeline medium temperature is very high, the pipeline outside the general design of the accompanying heat pipeline, and the two are wrapped together with a very thick thermal insulation material. Due to improper construction, many electromagnetic flowmeter flow tube is also wrapped in it, and even some accompanying heat pipeline to be wrapped around the flow tube a few times, accompanying heat is generally used 0.35MPa steam, the temperature reaches 150 ℃ or so. Therefore, the flow tube around the ambient temperature is very high, up to 100 ℃ or more, while the electromagnetic flowmeter requires a high ambient temperature of 60 ℃.
Improper grounding and external interference affect the normal operation of the flowmeter electromagnetic flowmeter signal is relatively weak, only 2.5-8mV at full scale, the flow rate is very small, the output is only a few microforms, the outside world slightly interfere with the measurement of the accuracy can be affected, so the electromagnetic flowmeter on the grounding requirements are very strict. Transmitter shell, shielded wire, measuring conduit and conduit ends of the pipe should be grounded, and requires a separate set of grounding points. If the electromagnetic flowmeter is found to indicate fluctuations and large amplitude, often over-range phenomenon. It is believed that on the one hand, it is due to the high sensitivity of the flowmeter, and the main reason is due to improper construction and cause the detection part of the external interference, which is mainly reflected in the following aspects.
Construction Irregularities To minimize disturbances created by bends, valves, and reducers in the process piping, the flow pipe installation process requires a minimum of 10D and 5D of straight piping before and after each.
Hangzhou Economic Development Area，Hangzhou 310018，China
