Hydraulic Filtration: Ingression Sources and the New Standard

Hydraulic Filtration Systems on Pipe Bending Equipment

Hydraulic filtration

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


    As you know from our previous article, 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.

Sources of Ingression

    In a hydraulic system, a 40 micron size particle can cause a catastrophic failure.  It can cause a valve to stop shifting or a pump to lock up.  One of the primary sources of ingression in a hydraulic system on mobile equipment is the air breathers on the reservoir.  At DMI we utilize 5 to 10 micron filtration for the breathers on the reservoir because 5 micron is much more efficient than 40 micron at keeping large dust particles out of the reservoir.  A large breather must be used in order for the large volumes of air to pass in and out of the reservoir.  During a normal cycle of the Stiffback circuit 25% to 35% of the hydraulic oil volume in the reservoir is exchanged.  Hence, large air flow capacity is required for the reservoir breathers. 

    The hydraulic cylinders are the second culprit for sources of ingression in a pipe bending machine hydraulic circuit.  Rod wipers do an excellent job of keeping the rods clean as the cylinders stroke up and down. Unfortunately, ultra fine particles still find their way under the rod wiper and into the hydraulic system. 

New Standard for Filtration

    We have a new standard for filtration at DMI.  All new DMI designed equipment is supplied with three micron filtration.  Our experience shows that the industry standard ten micron filtration systems are insufficient in removing the contamination found in hydraulic pipe bending equipment.  

    Similarly, DMI filters the hydraulic oil supplied in drums with a three micron offline filtration system.  And the same filtration cart is used to transfer the oil from the drum to the hydraulic reservoir on the pipe bender.  We believe this process improves the roll out quality of our equipment and provides our customers with the most reliable equipment. 

   Improved filtration systems is another way that DMI is continuously improving its equipment to deliver improved performance to our customers

Written by: Pat Kinnison and Chrystal Bates

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