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High Viscosity Oil Filtration

Effective kidney-loop filtration of high viscosity gear oils can be very challenging, especially at cooler ambient temperatures.  Proper sizing of the pump/motor and filter elements for optimal filtration performance is always important, but it takes on even more significance with high viscosity gear oil (ISO VG 220 – ISO VG 680). 

The first challenge for a kidney-loop filtration system on high viscosity gear oil is proper pump/motor selection.  Most off-the-shelf filter carts are designed for use with low viscosity hydraulic oils, and when they are used on a gearbox full of ISO VG 320 gear oil, the pumps will tend to cavitate, trip breakers, and/or burn up the motors due to heavy load.  The viscosity/temperature curve for gear oils is quite steep, so this potential problem is amplified with cooler ambient oil temperatures. 

The second challenge for a kidney-loop filtration system on high viscosity gear oil is proper filter element selection.  Effective filtration performance is all about surface area, and what works well on low viscosity hydraulic oil is usually woefully inadequate on ISO VG 320 gear oil.  It is not uncommon for the clean initial pressure drop through small spin-on filter elements on off-the-shelf filter carts to exceed 10 PSID, which results in very short life and inefficient filtration performance.  In this case, size really does matter!

At Oil Filtration Systems, we size every kidney-loop filtration system based on the customer’s specific application data, taking into account the oil viscosity and worst-case (coldest) oil temperatures.  By doing this, we can ensure that the pump/motor on every system runs properly with long life and reliability, and that the filter elements are sized properly to quickly and reliably achieve your target ISO cleanliness codes.

Check out our series of High Viscosity Filter Elements (HVF), which are designed and built with more surface area and support media to withstand the rigors of high viscosity gear oils and to achieve lower ISO cleanliness codes, faster!  

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