What are the different standards used in carrying out particulate checks?

Counting particles reveals how many solid contaminants there are in the oil sample analysed and how big they are.
Counting particles provides essential information for monitoring: 

• The cleanliness levels of fluids used in circuits that require products that are completely free of solid pollutants.
•  And / or the efficiency of the filtration system.

Various standards are used for checking articulations:
- ISO 3722: For approving and checking container cleaning methods.
- ISO 4021: Describes the various procedures for extracting samples from a system in operation.
- ISO 4405: Describes the method used for determining the total mass of pollutants obtained by filtration.
- ISO 4406: Defines a method for coding pollution levels.
- ISO 4407: Describes the method used to determine the level of particulate pollution by counting the particles under an electronic microscope.
- ISO 11500: Describes the method used to determine particulate pollution using an automatic particle counter that works according to the light-extinction principle.
- NAS 1638: Defines a method for coding pollution levels  (a different method to the one described in ISO 4406)
- SAE AS4059E:  Equivalent to NAS 1638, developed as its successor.

It is noted that the most frequently referenced standards (ISO 4406 and NAS 1638) only relate to the format in which the results are expressed, not the methods used to take samples or perform analyses.