Purvis Industries

By: Steve McKown

The life blood of the hydraulic system is the fluid, and it is usually the last thing customers think about.  Contamination in the fluid causes wear and damage to the moving components inside a system and can cause it to fail prematurely.  Here are some key points on filtration.

New hydraulic fluid: New fluid should be filtered before it is used.  Contamination gets into the fluid during the processing and packaging phases.  Filter carts are available to clean this fluid before use.  

Cleaning the tank: If the filters in the system clog they will bypass and return unfiltered fluid to the tank.  Particles settle out of the fluid over time leaving a layer of gunk at the bottom of the tank.  Most tanks have a panel that can be removed to clean this out.  Keeping the tank clean will increase the life of the filters. 

Suction filters in the tank: In the past most tanks were equipped with a screen suction filter on the suction tube.  The tank manufacturers are going away from this because if the screen clogs it can pull a vacuum on the pump causing a catastrophic failure.  They now rely on the high and low-pressure filters to catch debris in the system.  This makes the high-pressure filtration even more important.

Desiccant Filler Breathers:  Moisture acts like an abrasive in the hydraulic systems and can cause severe damage.  Using a desiccant breather cap removes the water vapor from the air. 

Return Filter:  this is the filter you will see most often on the power units.  This cleans the fluid as it returns from the system and removes the particulates introduced into the fluid by the seals, hoses, and moving parts in the system before returning to the tank.  If you have a worn rod seal on a cylinder it will pull dirt into the cylinder contaminating the fluid.  If you have older hoses they deteriorate and dirty the fluid.  

High-pressure filter:  This filter cleans the fluid coming out of the pump before it goes into the system.  The main purpose of this is to remove any of the wear particles that the pump produces.  It also prevents damage to the system if the pump fails for any number of reasons. 

Testing your fluid:  Donaldson has fluid testing available and we stock the test kits.  Testing the fluid does more than just tell you the oils dirty.  They examine the particulates in the oil and can report on the health of your system components since each item (pump, hoses, cylinders, valves, etc.) produces a specific type of contamination.

Reach out to one of our sales representatives to learn more on how we can assist you with your filtration needs.