Outlining the working principles of a magnetic level gauge

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Magnetic level gauges are used to detect and monitor the levels of liquids in demanding environmental conditions.

They operate on the principle of communicating vessels, which refers to separate containers that are connected via extrusion outlets to allow low- or high-density fluids of either homogenous or heterogenous consistencies to flow between the vessels.

The chamber, or auxiliary column, of the magnetic level gauge is equipped with a float containing a set of permanent magnets. Fluctuations in the fluid of the primary chamber will result in commensurate changes within the magnetic level gauge. The magnetic float rises and falls on the surface of the fluid, registering these changes on the external measurement indicator. This indicator is typically constructed using a magnetized shuttle that moves in conjunction with the interior magnets.

This technique is advantageous as it does not require restrictive mechanical guide rails and instead relies on the limited lateral motion of the float within the column of the magnetic level gauge. It is also suitable for fluid mixtures of varying densities, with variable float designs and materials suitable for the specific gravity of numerous measured fluids, including acids, butane, oils, water, and heterogenous fluid interfaces.   

Magnetic level gauges are increasingly preferable to alternative level measurement systems owing to their improved thermodynamic resistances over apparatuses such as sight gauges. They can withstand high process temperatures and are optimized for high pressure applications. Unique process demands can also be met using bespoke magnetic level gauges with oversized columns and floats with improved buoyant characteristics.

Magnetic Level Gauges from ABB

At ABB, we provide a range of established magnetic level gauges for some of the most demanding process industries. Our fluid level measurement instruments have been installed in over 200,000 installations worldwide with virtually maintenance-free requirements for total and interface level detection in the oil and gas, petrochemical, power generation industries, and more. These magnetic level gauges include:

  • The KM26 Magnetic Level Gauge: a low installation high-visibility component with extruded outlet connections and a chamber fabricated from a choice of non-magnetic metals;
  • The ABB MagWave: a close-coupled dual chamber system for redundant level measuring with the accuracy of guided wave radar transmitters at pressures of up to 207 bar;

Our magnetic level gauges can be engineered from a range of materials including Kynar plastics and metal alloys such as Hastelloy C-276, titanium, Incoloy, and Monel. These can be configured for unique application requirements, with considerations for extremely corrosive media and high ambient or process humidity levels. Bespoke chamber designs have been designed with magnorestrictive capacities to provide highly-precise level indications suitable for 4-20 mA electronic communications and further process interfacing.

If you would like any more information about our full range of magnetic level gauges and level sensing accessories, please find your local contact below.

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