Selection of magnets for magnetic flap floats
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I’m almost a complete novice when it comes to magnetic flap level gauges. I currently have a level detection device that can be designed by drawing on the principle of magnetic flaps and magnetic switches used in such gauges. However, I’m not familiar with the selection of magnets for use in these flaps, nor with the choice of appropriate magnetic switches. I hope that teachers who have experience in designing magnetic flap level gauges or who are knowledgeable in this area can kindly offer their guidance. The operating conditions are as follows: temperature of 550°C and pressure of 5 MPa. For the outer cylinder, I plan to use stainless steel 321 or 304H. I’ve looked up information on magnetic materials online, but I’m not entirely sure about it; it seems that for such temperatures, aluminum-nickel-cobalt magnetic materials should be used, but I’m not aware of which specific model to choose. This seems to be related to the magnetic energy product and residual magnetism of the magnetic material ； Additionally, I would like to know whether the thickness of the stainless steel outer cylinder affects the magnetic induction strength (or residual magnetism) of the magnet. If so, are there any resources that can help determine the magnitude of this effect? ； To be able to act on the magnetic switch, how is the magnetic induction strength of the magnet taken into account? Is a higher value better, or does it need to be kept within a certain range? ； Are there any requirements regarding the distance between the magnetic switch and the outer cylinder, as well as the method of installation? By the way, does the size of the magnet affect the magnetic induction strength (remanent magnetism)? How can I determine that?
It’s fine to use stainless steel for the main pipe; magnets made for high temperatures can also be used, and magnetic switches should likewise be of the high-temperature type
Why choose a magnetic flap? Even with such products, reliability decreases. It is recommended to use the differential pressure method for measurement.
So, which model of magnet should I choose? My thinking is that the greater the residual magnetism of the magnet, the more likely it is that the magnetic switch will function even when it is far away. However, if the measuring tube of the instrument is relatively short, it is possible that the float, no matter where it is in the tube, will trigger the magnetic switch. To use an inappropriate example: if I choose a magnet that can affect the magnetic switch within a range of 500 mm, while my measuring tube has a range of only 450 mm, then when the magnetic switch is attached to the measuring tube, wouldn’t the situation I mentioned earlier occur? In that case, the magnetic switch would send a signal regardless of where the float is located To be more precise, what I want to figure out is the relationship between the residual magnetism of the magnet used and the radius over which the magnet causes the magnetic switch to function. Is there a formula for this calculation, or is there some approximate relationship between residual magnetism and this range of influence? Also, does the stainless steel tank have an impact on the magnetic induction strength of the magnet?
The measuring device I plan to build is not designed for measuring liquid levels; it merely needs to make use of the principle of signal transmission in magnetic flap level gauges. However, I am not familiar with how to choose the residual magnetism of magnets used in such devices, nor with the distance over which these magnets can affect magnetic switches. That’s why I’m posting this question to seek advice from experienced professionals
1. If you really want to study it, do the experiments yourself. 2. For domestic magnetic flap valves, I don’t use magnets at all; over time their magnetism weakens, and they eventually become unreliable. I buy strong magnets on my own to use as a replacement. The downside is that the outer flap is no longer completely red in the liquid level area; instead, at the position corresponding to the liquid level interface, the flap moves between red and white, meaning it’s essentially just one point. As for the other areas of the flip board, it doesn’t matter whether they are red or white. 3. The original magnets are very small, with an outer diameter of no more than 10 mm, and two are installed. And most of my strong magnets are 35mm, installed individually. 4. The magnet strength, magnet size, and gap between the flap all affect whether the flap can move in a consistent and reliable manner. But I don’t care anymore, because I’m a strong magnet – I can’t even move it, so how can it move? I just focus on being reliable.
How about this: add me on Q and I’ll chat with you. 568099860
At a temperature of 550 and a pressure of 5 MPa, magnetic flap level switches are not suitable; other types of level switches, such as float switches, can be used