electromagnetic flowmeter As a star product in the flowmeter industry, it has been widely used in our industrial field. However, many people think that the selection of electromagnetic flowmeter is too complicated. Today, Yijia editor will teach you how to make it convenient, fast and targeted YJ-LDE Correct selection of series electromagnetic flowmeter.
The first step is to measure the medium.
What is the medium to be measured? What are the ingredients? Is there any bubble? Is it conductive? Is there magnet interference? Whether there will affect the scaling phenomenon of sensor electrode and so on, which will directly affect whether the electromagnetic flowmeter can work normally or the electrode lining selection.
For example, if the fluid contains iron sand and other magnets, the magnetic field of the instrument will be disturbed and the corresponding error will be generated; if the fluid contains bubbles. The measured flow rate is the volume flow rate including bubbles; if the fluid has precipitation or scaling phenomenon. It will cause the electrode to be covered by foreign matters and cause the zero point fluctuation of the instrument. The particles in the fluid may impact the electrode and form a sharp noise. The stability of flowmeter indication is affected. In this case, porous ceramic or conductive rubber covered electrode electromagnetic flowmeter can be used.
The most important premise of electromagnetic flowmeter is that the measured liquid must be conductive and not lower than the threshold value (i.e., the lower limit). If the conductivity is lower than the threshold value, the measurement error will occur until it can not be used. If the conductivity exceeds the threshold value, it can be measured even if it changes. The indication error does not change much. The threshold value of the universal electromagnetic flowmeter is at 10-4 ～（ five × 10-6 ） S/cm There is a slight difference between the models.
Second step, temperature, pressure, caliber, flow rate, full flow rate and range
Temperature and pressure refers to the temperature and pressure in the pipeline. The size of pressure grade and temperature will directly affect the selection of electromagnetic flowmeter. Therefore, the range of pressure and temperature in the pipeline must be confirmed when selecting the type.
The diameter refers to the matching with the measuring pipe, but it must be exactly the same. The diameter of the flowmeter should match the flow rate of the medium. If the measuring range is too large or too small, it will directly affect the electromagnetic flowmeter, even can not be used.
When the electromagnetic flowmeter is full flow, the liquid flow rate can be in the range of one ～ 10m /s Within the scope of selection, the scope is relatively wide. The upper flow rate is unrestricted in principle, but it is generally recommended not to exceed 5m /s Unless the lining material can withstand the erosion of liquid flow, the actual application rarely exceeds 7m /s , more than 10m /s It is even more rare. The lower limit of full flow rate is generally 1m /s Some types of instruments are 0.5m /s 。 At this time, from the perspective of measurement accuracy, the diameter should be smaller than the pipe diameter.
The third step is to select the accuracy level
There are great differences in the performance of domestic electromagnetic flowmeters. Some of them have high precision and many functions, while others have low precision and simple functions. The basic error of high precision instrument is (± 0.5% ～± 1% ）。 The instrument with low precision is (± 1.5% ～± 2.5% ） FS The price difference between the two one ～ two Times. Therefore, it is not economical to select high-precision instruments in places where the measurement accuracy is not very high. On the contrary, under the working conditions with high accuracy requirements, low-precision products must not be used to replace the inferior ones.
The three points summarized by wangyijia can help you select the most suitable electromagnetic flowmeter products for your own working conditions.