Magnetic filter keeps fluids clean

June 16, 2005
When their motorcycle engines kept failing due to hard, ferrous contaminants, two Brits invented the Magnom filter. Its simple design uses no moving parts.

Instead, magnetic fields capture ferrous and nonferrous objects as small as 1 m. Though originally intended to keep fuel systems clean, it is now used on hydraulics, transmissions, and lubrication systems as well. The filter is distributed by FCS, Warwick, England (

The device has wide flow channels between stacks of plates that let fluids pass with minimal pressure drop. A magnet draws ferrous and nonferrous contaminants into collection zones between the plates. (The filter collects nonferrous particles if ferrous ones are present in a process called heterocoagulation.) These zones hold significantly more contaminant than conventional filters and without obstructing flow. Therefore, the Magnom operates for long periods without service and is easily cleaned and reused. It cannot puncture and dump contaminants into the system. And it works with fluid flowing in either direction, and even both directions if it is a pulsing system. The filter withstands fluid pressures to 140 bar, flows up to 500-liters/min, viscosities to 10,0000 cST, and temperatures to 350°C.

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