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 Magnetic Level Gauge

Left drawing shows a typical BONT® Magnetic Level Gauge, used in level control of any kind of fluid.
The Magnetic Level Gauge is the instrument to read a level indication in whatever plant or operating conditions giving free  maintenance, preventive security against leakage, environmental safety, sure and trouble free application with chemically aggressive, pollutant, harmful or poisonous, inflammable or explosive, optically similar fluid interface.
Our very wide range of Magnetic Level Gauges allows to have the proper instrument for any kind of plant or specific purpose. Our world patented system includes a float able to float both in high density fluid or in low density fluid up to 0.4 specific gravity. But more! You can have low specific gravity and high temperature and pressure together (i.e. water/steam of H.P. vessels). Well! We manufacture a float able to float and to resist with external pressure of 210 bar at 370 ºC!.And more! Do you need Remote Direct Reading
? We have it, as a completion of Magnetic or Glass level Gauge. Are you looking for a Transmitted Remote Signal? We can supply a sensing element able to transduce the signal to LED, Analog or Recording Instruments that you can have in the Control Room.

In a vertical chamber (tube of suitable diameter connected by stub ends to the vessel) there is a float containing a permanent magnet -fixed by means of special patented device that permit to the magnet a 360º rotation- placed exactly on liquid level line.
Magnetic action of permanent magnet in the float generates rotation of a set of small permanent magnets enclosed in small cylinders-contained in indicating scale-which cylinders, having different colors in the North and South pole, can rotate on their horizontal axis.

So the scale appears of one color (i.e. white) over chamber area taken by gas and of another color (i.e. red) over chamber area taken up by liquid phase.
The chambers of the Magnetic Level Gauge are dimensioned  according to ASME B31.1 and B31.3.
The chamber is connected to vessel with flanged, threaded or welded ends. Usually, between the instrument and its connecting ends valves are fitted to consent shut-off piping and to disassemble the level gauge without empting the vessel or shutting off the plant. Drain valves can also be fitted on the top and bottom of level gauge.



Operation of BONT Magnetic Level Gauge is based on  some elementary physical principles:

  • The principle whereby liquid in communicating vessels is  always at same level;
  • Archimede's principle according to which a body immersed in a  liquid receives a buoyancy equal to the weight of displaced  liquid;
  • The principle of attraction between North and South poles of  two permanent magnets and that of repulsion between like poles.
    • This principle has two applications in the BONT  magnetic level gauge:
      • first between the magnet in the chamber float  and every single magnet of the indicating scale:
      • second between the magnets of the indicating  scale.
The cylindrical magnet "A" in the float is able to  turn horizontally on the axis "B" like a compass needle, so that  magnetic force is always free to best orientate itself towards the  magnetic scale, in which small cylinders "C", rotating vertically on  their axis "D", contain smaller cylindrical magnets fitted in  orthogonal position to rotation axis.
Cylinders No. 1 & 2 are  in stable position, as cylinders 4 & 5, because the magnetic  chain between their magnets is well oriented "N-S-N-S"; cylinder No.  3 is in not stable position because North Pole "N" of the bigger  magnet "A" inside the float attracts the South Pole "S" of the  smaller magnet inside the cylinder. The same cylinder tries to  rotate clockwise because its "N" pole would reach the "S" pole of  cylinder 2. Imagine now that fluid, growing in the level gauge,  pushes up the float. The float magnet, going upside, will approach  the cylinder 4, attracting its "S" pole, and so, after clockwise  rotation, it will be in the same position as now the cylinder 3.  Same cylinder 3 will be in that case free to complete rotation  clockwise, and its position will became stable as cylinder 1 &  2. And so and so with growing of the liquid level. The same, with  inverse rotation of small cylinders, happen when the float goes  down.

Remote Direct Reading (RDR) Magnetic Gauge
With the use of electronic sensers remote direct reading from afar is easily achieved with the RDR Magnetic Gauge. The system may be connected to a cherry system, LED connector or a Transducer with an Analog converter for connection to a digital device or indicator. The system can be installed on any boiler or tank. Only two connections is sufficient for installation.  



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