Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1080534
www . machinerylubrication.com | January - February 2019 | 15 TARGET ISO 4406 CLEANLINESS CODES LOW/MEDIUM PRESSURE UNDER 2,000 PSI HIGH PRESSURE 2,000 TO 3,000 PSI VERY HIGH PRESSURE OVER 3,000 PSI ISO Target Levels Micron Ratings ISO Target Levels Micron Ratings ISO Target Levels Micron Ratings PUMPS Fixed Displacement Gear or Vane 20/18/15 20 19/17/14 10 18/16/13 10 Fixed Displacement Piston 19/17/14 10 18/16/13 5 17/15/12 5 Variable Displace ment Vane 18/16/13 5 17/15/12 3 Not Applicable Not Applicable Variable Displace ment Piston 18/16/13 5 17/15/12 3 16/14/11 3 VALVES Check Valve 20/18/15 20 20/18/15 20 19/17/14 10 Directional (Solenoid) 20/18/15 20 19/17/14 10 18/16/13 5 Flow Control 20/18/15 20 19/17/14 10 18/16/13 5 Cartridge Valve 19/17/14 10 18/16/13 5 17/15/12 3 Proportional Valve 17/15/12 3 17/15/12 3 16/14/11 3 Servo Valve 16/14/11 3 16/14/11 3 15/13/10 3 ACTUATORS Cylinders, Vane Motors & Gear Motors 20/18/15 20 19/17/14 10 18/16/13 5 Piston Motors 19/17/14 10 18/16/13 5 17/15/12 3 OTHER Hydrostatic Drives 16/15/12 3 16/14/11 3 15/13/10 3 Test Stands 15/13/10 3 15/13/10 3 15/13/10 3 piston pump is the most critical system component and the maximum system pres- sure is 1,500 pounds per square inch (psi), then the target level would be 18/16/13. A 5-micron filter is necessary to achieve this target level. If the same pump is used in a system that operates at 2,500 psi, then the target level would be 17/15/12. More metal break- down occurs at higher system pressures. One or more 3-micron filters would be required to meet this target level. If the oil sample for the 1,500 psi system indicates a 20/18/12 level, then the system is not being maintained to the desired stan- dard of 18/16/13. is may be due to the filters not having the proper beta rating or the existing system filters being contami- nated and allowing oil to flow through the internal bypass check valves (if used). Once the desired cleanliness level has been identified, the next step is to deter- mine where the filters should be located. Consider the following six system locations where contaminants can be removed. Reservoir Breather Whenever the oil level drops in a reser- voir, atmospheric air will flow through the breather. Many hydraulic units contain an inexpensive breather that doubles as a fill cap, but oil should never be added to the system without being filtered. Not only is it important to remove solid contaminants from the air but also to keep moisture out of the tank. Air contains water vapor, which can turn into liquid moisture once it cools down inside the tank. A desiccant breather can be used to remove the mois- ture from the air before it enters the tank. rough the use of an adapter, this type of breather can be mounted on the same base as the existing, old-style breather. e desiccant crystals will change color as the moisture is absorbed. Most desiccant breathers contain a 3-micron internal filter for removing solid particles from the air. Your selected breather should also have a visual dirt alarm to indicate the condition of the particulate filter. Pump Suction Filter e purpose of a suction filter is to prevent large particles from entering the pump. is filter may be in the form of a strainer located underneath the fluid level. ese strainers usually have a 74- or 149-micron rating. I recently consulted with a corrugated box manufacturer which had changed ML These target ISO 4406 codes indicate the required cleanliness levels for various system components.