What is Magnetic level gauge

Magnetic level sensors

Magnetic float level sensors involve the use of a permanent magnet sealed within a float, which rises and falls to open or close a mechanical switch through direct contact or proximity to a reed switch.For mechanically actuated floats, the float is directly connected to the microswitch.For magnetic and mechanical float level sensors, chemical compatibility, temperature, specific gravity (density), buoyancy, and viscosity can affect stem and float selection.For example, larger floats can be used for liquids with a specific gravity as low as 0.5 while still maintaining buoyancy.The choice of float material is also influenced by temperature-induced changes in specific gravity and viscosity these changes directly affect buoyancy.

Explanation 

Exploring the physics and engineering behind this design requires studying fundamental magnetism.A standard bar magnet has two poles: a north pole and a south pole.(North reads positive on a gauss meter, south reads negative.) Magnetic fields are drawn using flux lines.The lines are a graphical representation of the magnetic field density.They show the direction of flow of the magnetic field and represent the relative field strength the closer the lines are,the stronger the field.Flux lines will always travel from the north pole to the nearest south pole,and will always leave and enter the surface at 90° or perpendicular to the surface.They can only travel along straight or curved paths,which means they can never change direction abruptly and abruptly.The flux lines will also always follow the path of least reluctance. Most importantly,they can never cross each other.

Considerations

When selecting a magnetic level gauge,it is important to consider the strength of the magnetic field.Magnetic fields are at the heart of magnetic level gauges the stronger the magnetic field,the more reliable the instrument will operate.Some manufacturers' magnetic level gauges rely on a single magnet,which results in a North field that is as strong as a South field, but just as weak.Obviously,where the indicators,switches and transmitters are located,the magnetic field will not be as strong.Some manufacturers use a single ring magnet, others use a series of circular arrays of single magnets in their float designs.In this design, the relative magnetic field strengths of the north and south poles will be equal to each other and less than that of the dual magnet design.Also, as you go around the circle,there will be highs and lows in the magnetic field strength as you pass between the various bar magnets.