Causes and solutions for abnormal panel display caused by magnetic float of magnetic flap level gauge

As a manufacturer of magnetic flap level gauges , friends often call or email to ask about solutions to some problems in the use of magnetic flap level gauges. This article is an example of communication between users and technicians, mainly involving the use of magnetic floats of magnetic flap level gauges, which are summarized as follows:
 


User asked:
The magnetic flap level gauge purchased by the company before was very easy to use, but it cracked during use. The maintenance personnel later changed it twice, but it was not the original one. When it was replaced for the first time, the flap on the magnetic flap panel turned intermittently, and the second time the flap could not be turned directly. We confirmed that the parameters of the maintenance materials are configured according to the parameters of the original reprint, mainly the diameter and length, as well as the relevant temperature, pressure, density, material, etc. We can also brush the magnet back when we go to the site. The flap should not be a big problem and has never been disassembled or moved. So I would like to ask about the float. Is there a relevant standard for the magnetism of the float? Or is there something wrong? The float is installed in the correct direction and the medium pressure is normal. I really don't know how to report spare parts in the future with so many flaps. Is there any better way besides contacting the original parts?
 
The technician answered: The panel indication
of the magnetic flap level gauge is inaccurate. In many cases, the float of the magnetic float level gauge moves normally, but the panel indicates the wrong liquid level. The most common color display is intermittent, such as when there is no liquid level, part of the middle panel indication is red, or when there is a liquid level, part of the indication is white. The reason for this phenomenon is that the magnetic float moves up and down too much, causing the external panel magnetic column to move over before it can flip over. This fault often occurs when the liquid level changes drastically or when the instrument personnel maintain and drain.
 
Another situation is that the distance between the magnetic columns changes, causing the friction to increase, and the magnetic coupling between the magnetic column and the magnetic float cannot overcome the friction, causing the magnetic column to be unable to flip, or the magnetic force of the magnetic column becomes weak and the magnetic column does not flip. To deal with these faults, you can use an external magnet to slowly move from top to bottom or from bottom to top along the magnetic column that displays the error to make it display correctly, and then move up and down through the internal magnetic float to see if the panel indication is correct. If there is no magnet, you can also remove the plastic cover on the outside of the panel and use a screwdriver to wave the magnetic column to restore it to normal. If the magnetic column becomes weak, it can be removed and replaced.
 
Since the principle of measuring the liquid level of the medium by the magnetic flap level gauge is the constant buoyancy method, the float model should be selected according to the medium density. In actual use, the medium density usually deviates from the ideal value. Is the liquid level displayed by the float accurate? This is known after many tests. If the medium density changes, the detected liquid level will not be affected, because the float is a dynamic balance in use. If the medium density becomes larger than the set value, the buoyancy of the float becomes larger, and the height of its immersion in the medium will float up a little to reach a new balance. If the density decreases, the float will float down a little to form a new balance. Of course, the density cannot be greatly reduced, otherwise the buoyancy generated after the float is completely gone will be less than its own weight, and it will sink to the bottom and cannot float up. This situation is rare in actual applications, so in most cases, the medium density changes slightly around the selected value and does not affect the liquid level measurement.