Hydraulic Filtration: ISO Cleanliness

hydraulic filtration system cleans

Hydraulic Filtration

 New oil is dirty oil and should be the only dirty oil your system ever sees.


    That’s right, the mineral oil you purchase from your local supplier in your totes or in your 55 gallon drums is dirty.  Purchasing clean oil is cost prohibitive for most manufacturers of hydraulic equipment. As the new oil passes through the system the filters will do their job and clean up that dirty new oil. Hence, properly designed hydraulic filtration systems on pipe bending equipment will clean up that dirty oil and bring it within the system requirements for your valves and pumps.

ISO Cleanliness

    Every hydraulic system has an ideal ISO cleanliness level that should be maintained for it to operate correctly and efficiently. Every component in the hydraulic system has an ISO recommended cleanliness level for that component to operate correctly.  Components with tight clearances between parts (ie: a valve spool and body)  may require a more stringent cleanliness level than a gear pump. 


    Using a fluid analysis service will provide you with the concentration levels of Additives, the Total Acidity Number of the oil and the ISO cleanliness of the oil.  These three items will help you make an informed decision whether or not you should change your oil. A fluid analysis will also report the amount of water in the hydraulic oil. Excessive water in the oil will cause foaming, reduce viscosity and excessive wear.  While water is a contaminant found in many hydraulic systems I have not found it to be an issue on pipe bending equipment.

Silver Lining

    With all of that being said, there is a silver lining to keeping your hydraulic oil clean.  Research shows that equipment which operates with oil maintained to the required ISO cleanliness level will last at least three times longer than equipment that is not designed accordingly. 

    Longer service life is a value we strive to provide our customers.  We take extra steps to clean our new oil and provide three micron filtration in all of our new equipment. In the next article in this series we’ll discuss how to determine the service intervals for the hydraulic oil.

Written by:  Pat Kinnison and Chrystal Bates
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