MACHINERY LUBRICATION- INDIA NOVEMBER-DECEMBER 2019 | Page 28

Devin Jarrett | Noria Corporation
BACK PAGE BASICS
Particle Counting
Particle Counts:
What They Mean
and How to Use Them
“By better
understanding
the ISO
cleanliness
code, setting
appropriate
targets
and closely
monitoring
your particle
counts, you can
determine how
dirty or clean
your oil is.”
When my wife and
I started getting
serious about the
future during our
love-struck dating days, we began
talking about what kind of family
we envisioned. We both wanted a
large family and for our kids to be
close in age in hopes they would
have a closer bond when they
became adults.
Fast forward a few years, and we
had our first four children within
five years. Little did we know that
the impact of each additional child
would be more of a multiplication
factor than simple addition. When
our youngest turned 5, we decided
we wanted one more and chose to
26 | November - December 2019 |
adopt a fifth child, knowing full
well that life would double for us
once again.
Much like the multiplication
factor for how quickly our home
requires a deep cleaning based on
the number of children we have,
how clean or dirty your oil is can
be determined by multiplying the
number of particles in the fluid,
according to the cleanliness code
developed by the International
Organization for Standardization
(ISO).
Understanding the
ISO Cleanliness Code
To fully understand the ISO 4406
solid contaminant standard, you
www.machinerylubricationindia.com
need to go back to the beginning.
Surprisingly, this standard did
not originate with ISO but rather
the National Aerospace Standards
(NAS) organization. During the
1960s, the NAS attempted to
bring order to the chaos of particle
counts in aircraft hydraulic fluids.
The result was the creation of
NAS 1638.
The first version of this standard
utilized an optical microscope
to size solid particles. All the
particles within 1 milliliter of oil
would be categorized into five
size ranges: 5-15 microns, 15-25
microns, 25-50 microns, 50-100
microns and greater than 100
microns. A chart was used to