Page 14 - Parker - The Handbook of Hydraulic Filtration
P. 14
Fluid Cleanliness Standards
Filtration Fact In order to detect or correct problems, The ISO 4406:1999 (International
a contamination reference scale is
Standards Organization) cleanliness
used. Particle counting is the most level standard has gained wide accep-
Knowing the cleanliness
common method to derive cleanliness tance in most industries today. This
level of a fluid is the basis
level standards. Very sensitive optical standard references the number of par-
for contamination control instruments are used to count the ticles greater than 4, 6, and 14 microm-
number of particles in various size eters in a known volume, usually 1 mil-
measures.
ranges. These counts are reported as liliter or 100 milliliters. The number of
the number of particles greater than a 4+ and 6+ micrometer particles is
Filtration Fact certain size found in a specified used as a reference point for “silt” par-
volume of fluid. ticles. The 14+ size range indicates the
The ISO code index quantity of larger particles present
numbers can never which contribute greatly to possible
catastrophic component failure.
increase as the particle
sizes increase
(Example: 18/20/22).
All particle distributions
have more smaller than ISO CODE 19 / 16 / 13
larger particles.
Particles
> 4 microns (c)
Particles
> 14 microns (c)
Particles
> 6 microns (c)
An ISO classification of 19/16/13 can be defined as:
Range Number Micron (c) Actual Particle Count Range (per ml)
19 4+ 2,500 - 5,000
16 6+ 320 - 640
13 14+ 40 - 80
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