Scanning for Ideas: Magnet Keeps Contaminants Out of Fluids

Feb. 7, 2008
In oil-lubrication or hydraulic systems, it’s the small submillimeter pieces of tool steel that cut up and destroy motors, pumps, and other hardware.

If you can keep those out of the fluid lines, you’re well on your way to a contaminant-free system. With this in mind, engineers at Magnom, Chicago (, decided to revisit the magnetic filter and came up with Magnom core technology. It sandwiches a relatively strong donut-shaped magnet between two steel discs to make up a core. Several cores can be stacked on a central mandrel to meet application- specific requirements. The magnet is configured so that its north and south poles are on its flat sides, extending the north and south-oriented magnetism to the discs. The discs also have cutouts large enough to carry the required fluid flow.

The discs concentrate magnetic forces between the outer portion of the discs. These forces pull out steel and ferrous particles, down to 0.1 μm, out of the fluid and holds them tightly in the area between discs, the collections zone. Conversely, the magnetic fields interact to keep fluid-flow cutouts clean. So as the filter collects debris, clogging the space between the discs, the fluidflow areas remain clean, letting the required flow through.

The filter generates no pressure drop across it, can be installed on the suction side of a pump without risking cavitation, and works whether it is a continuous or pulsating flow. It handles pressures up to 140 bar, flow rates of up to 500 lpm, viscosities of 10,000 cST, and temperatures to 350C.

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