Manufacturers of magnetic level gauges explain in detail the causes and failures of demagnetization
the magnetic level gauge
will encounter the phenomenon of demagnetization. To understand why a magnet is demagnetized, we must first understand the principle of magnetism. The magnetism of a substance is a magnetic field generated by the rotation of electrons inside the atom around the nucleus. It can be imagined that each The motion of electrons is a magnetic field generated by passing a current through a single-turn coil, but the magnetic fields generated by the motion of electrons in the atoms of most elements cancel each other out, so there is no magnetism. Only the atoms of the three elements of iron, cobalt, nickel, and electrons The magnetic field generated by the motion is not offset, so it is magnetic. The two poles of a magnetic field exist at the same time, and it is impossible for one magnetic pole to exist alone. A magnet is actually made up of many tiny magnetic poles. The so-called soft magnetic material is that when an external magnetic field is applied, the small magnetic poles can be aligned uniformly, and when there is no external magnetic field, the small magnetic poles become disorderly arranged under thermal motion and do not show magnetic properties to the outside. For permanent magnets, after being magnetized, each small magnetic maximum body has the same arrangement direction (ie, the magnetization direction), so it is combined into a large magnet. When the external magnetic field is removed, these small magnetic poles can still be aligned and show magnetic properties to the outside.
Therefore, degaussing means demagnetizing the different magnetic directions of each molecule of a magnetic material. What we usually call a sex magnet is not a permanent magnet. External factors will change its magnetism. Not only will it be hot, but it will also lose its magnetism due to impact. Strong magnetic fields can also change its magnetic poles and its magnetic strength. Magnetic fields generated by alternating currents of varying sizes can quickly demagnetize magnetic bodies.
The high-temperature magnetic flap liquid level gauge works permanently in a high-temperature environment, so the magnetic float will have a demagnetization phenomenon during the use of the magnetic float, which will cause the magnetic flap liquid level gauge to fail. High-temperature magnetic flap liquid level gauges (especially high-temperature and high-pressure magnetic flap liquid level gauges) are generally used at temperatures exceeding 180 degrees Celsius, and their installation and disassembly are dangerous.
The solution of the demagnetization phenomenon of the magnetic level gauge can be divided into the following aspects:
A. From a design point of view, it is necessary to choose appropriate hard magnetic materials. For example, select the magnetic material whose Curie temperature is higher than the use temperature by more than 20% and ensure that the residual magnetism exceeds the critical value after five years. Runzhong Instrument has been producing magnetic flap level gauges for many years. It is not sloppy in terms of material selection. The materials are made of high-quality raw materials. In order to ensure stable and reliable performance, some key original components are imported products.
B. From the perspective of production, pay attention to the following points when processing magnetic floats:
1. When welding (argon arc welding), cooling measures need to be taken to avoid that the temperature of the magnetic material of the magnetic float exceeds the Curie temperature of the magnetic material.
2. The magnetic float is filled with an inert gas (such as argon);
C. From the perspective of use, users need to do the following:
1. Select the appropriate model when ordering so that the use temperature does not exceed the nominal temperature of the magnetic flap liquid level gauge;
2. In use, you should always observe the use of the magnetic flap level gauge (whether it can be used normally), and also record the actual temperature of the medium (I have seen this situation, the actual use temperature is often higher than the parameter table The temperature, the person who designed the parameter table may have overlooked some factors).
As a commonly used instrument for measuring liquid level, magnetic flap level gauge has the advantages of simple structure, convenient use, stable performance, long service life, easy installation and maintenance, etc., and is widely used in petroleum processing, food processing, chemical industry, water Level measurement, control and monitoring in processing, pharmaceutical, power, paper, metallurgy, marine and boiler industries. However, during the detection process, due to the influence of interference factors, the following faults will occur in the magnetic levitation ball level gauge, which will affect the accuracy of the measurement results. Therefore, let's understand the problems of the magnetic levitation level meter:
1. After the level gauge is put into use for a period of time, it appears that the float is difficult to float and the float is not sensitive to movement. This is basically caused by iron filings or other dirt on the magnetic float. The medium can be emptied first, and then the float can be taken out to eliminate iron filings or other dirt on the magnetic float.
2. During the on-site adjustment, I accidentally found that the float is not sensitive enough to move up and down. This is mostly caused by the improper level gauge device. At this time, pay attention to whether the center of the upper and lower flanges can be on a line and whether it is perpendicular to the level plane. Generally speaking, the angle with the degree plane is not less than 87 degrees. If the deviation is large, it may affect the smooth movement of the float.
3. Select intrinsically safe liquid level timer, pay special attention to whether the impedance of the liquid level meter and the safety grid can match.
4. The magnetic levitation ball level gauge is adjusted normally. After being put into use, it is found that the float shows a "suck" phenomenon in a certain position for a period of time. This is mainly caused when the level gauge passes through the steel platform device and is too close to the steel plate. Therefore, it is necessary to pay special attention to the distance between the pipe wall of the liquid level gauge and the cutting edge of the platform through the steel platform device.
5. During the use of the level gauge, if the output signal generates frequent disturbances or interference pulses, it is necessary to check whether the signal cable shielding layer can be firmly grounded and whether the working connection resistance can meet the request.
6. When the level gauge is put into use on site, pay special attention to the upper gate valve should be opened first, and then the lower gate valve should be opened later. This is because the bottom of the liquid level gauge communication tube is equipped with a thrust spring to maintain the float. Otherwise, the effect of large differential pressure may break the float and cause the liquid level gauge to fail to operate.
7. If the sealed glass tube used for on-site instructions breaks due to transportation or other reasons, it can be replaced with domestic glass tube. But can be evacuated. Also pay attention to whether the glass tube is vertical, so as not to affect the indication of the indicator.
8. Pay special attention when using the magnetic float ball level gauge. Do not use a strong magnet to pull the float up and down the outside of the communication tube to stop the inspection. Otherwise, it will cause the magnet float to magnetize and change its polarity, which will weaken the float magnet and make it difficult to normal jobs.