ISO Cleanliness Levels

Finding the cleanliness level required by a system

1. Starting at the left hand column, select the most sensitive component used in the system.
2. Move to the right to the column that describes the system pressure and conditions.
3. Here you will find the recommended ISO class level, and recommended element micron rating.

	Low/Medium Pressure Under 2000 psi (moderate conditions)		High Pressure 2000 to 2999 psi (low/medium with severe conditions¹)		Very High Pressure 3000 psi and over (high pressure with severe conditions¹)
	ISO Target Levels	Micron Ratings	ISO Target Levels	Micron Ratings	ISO Target Levels	Micron Ratings
Pumps
Fixed Gear or Fixed Vane	20/18/15	20	19/17/14	10	18/16/13	5
Fixed Piston	19/17/14	10	18/16/13	5	17/15/12	3
Variable Vane	18/16/13	5	17/15/12	3	N/A	N/A
Variable Piston	18/16/13	5	17/15/12	3	16/14/11	3²
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
Standard 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	3²
Servo Valve	16/14/11	3²	16/14/11	3²	15/13/10	3²
Actuators
Cylinders, Vane Motors, Gear Motors	20/18/15	20	19/17/14	10	18/16/13	5
Piston Motors, Swash Plate Motors	19/17/14	10	18/16/13	5	17/15/12	3
Hydrostatic Drives	16/15/12	3	16/14/11	3²	15/13/10	3²
Test Stands	15/13/10	3²	15/13/10	3²	15/13/10	3²
Bearings
Journal Bearings	17/15/12	3	N/A	N/A	N/A	N/A
Industrial Gearboxes	17/15/12	3	N/A	N/A	N/A	N/A
Ball Bearings	15/13/10	3²	N/A	N/A	N/A	N/A
Roller Bearings	16/14/11	3²	N/A	N/A	N/A	N/A

¹ Severe conditions may include high flow surges, pressure spikes, frequent cold starts, extremely heavy duty use, or the presence of water

² Two or more system filters of the recommended rating may be required to achieve and maintain the desired Target Cleanliness Level.