ISO Cleanliness Levels

LOGO_Hydac

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

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
Servo Valve 16/14/11 16/14/11 15/13/10

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 15/13/10
Test Stands 15/13/10 15/13/10 15/13/10

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 N/A N/A N/A N/A
Roller Bearings 16/14/11 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.

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