There are three
principal methods to measure the contamination level in a component, circuit,
or system.
The methods are: Gravimetric Measurement (ISO
4405); Particle Size Distribution Analysis (ISO 4406 or NAS 1638); Maximum
Particle Size Analysis (ISO 4407).
This discussion will cover Gravimetric Measurement.
Gravimetric
Measurement (ISO 4405) is a reporting method that references
the total mass of
contaminant
found in a hydraulic component. This total mass of contaminant measurement is
then normalized by the total internal component surface area of a hydraulic component.
A fluid is used to
dislodge
contamination in a hose assembly and is then poured through a
membrane catch filter.
An
analytical balance is used to measure the total mass of contaminate
which has been flushed out of a component. The total mass of contaminate and is
referenced to the surface area or volume of the assembly.
Gates
currently offers a system of four Gravimetric measurement (ISO 4405) levels of
cleanliness for hydraulic assembly that can be used to meet or exceed cleanliness
requirements.
