High Purity Northwest offers several options of kidney loop filtration systems and offline filtration systems.  Our kidney loop filtration system  ideal for removing solid particulate down to ISO 14/11/8 or better, as well as water.  Additional filter options allow for the removal of soft particles, sludge, varnish and acid from oil reservoirs.

Our offline filtration systems are commonly used by the U.S. Army Corps of Engineers to maintain clean and dry oil in the reservoir of governor control systems. Kidney loop filtration is also ideal for hydraulic oil, gear oil, refrigeration oil, and control oil systems.

Common sizes are 5 and 10 GPM, but are available from 2 GPM to 100 GPM (and above). High Purity Northwest manufactures custom kidney loop filtration systems to your requirements. We frequently add low watt density fin tube heaters with temperature control and a flow switch that shuts the system down under loss of flow conditions.  Water absorptive filter elements are used when water removal is required.

When soft particles, acid, sulfur or varnish is present, we offer a depth filter ideal to such removal requirements. These filter elements have superb acid control abilities without stripping additives. Depth filtration utilizes an absorption process.

Micro glass is used to remove hard particles from 2 micron and larger. Our glass filters, used in our kidney loop filtration, have a Beta rating of 1000 to provide the highest removal rate in the industry.  Our filter elements are state-of-the-art, utilizing a coreless design, a green solution for filtration, with a relief valve ideal for cold start up applications.  The integral filter element relief valve ensures peak performance of the filtration system; whereas internal bypass valves wear out over time and are a source of filter bypass.

Please contact us to discuss your kidney loop filtration system. We customize as required to meet your application needs.


  1. Azita Malek-Reply
    November 13, 2014 at 4:00 pm


    I would really appreciate if you could send me a catalog for your kidney loop filtration system. I am interested in the type that has heating element.

    Thank you very much.

    Azita Malek

  2. November 27, 2014 at 6:10 pm

    We are looking for a cost for a kidney loop filtration system for a 75 hp power unit (250 to 300 gallon reservoir) that will be added to a new transfer station trash compactor that we have on order from one of our clients.

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