With this change in the natural distribution of particles, ISO decided it was no longer necessary to report the concentration of these larger particle ranges. Filters became more efficient at removing larger particles, which made the larger size ranges less representative of the particle distribution in the oil. The improvements in particle filters tipped the scales of natural distribution.

With improved particle filters, the invention of automatic particle counters (and today's IoT fluid monitoring technology) and the push for ISO 9000 during the ’80s and ’90s, several other attempts were made to create industry standards for cleanliness levels by the Society of Automotive Engineers (SAE), the Aerospace Industries Association of America (AIA) and others. This method worked well and was largely accepted by industry through the 1970s and ’80s. Prior to this time, a coding system to quantify oil cleanliness had not been established. The lower the number, the cleaner the oil. A chart was used to classify the oil’s cleanliness with a range of 00 to 12, based on the number of particles in each size range. 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.

The first version of this standard utilized an optical microscope to size solid particles. During the 1960s, the NAS attempted to bring order to the chaos of particle counts in aircraft hydraulic fluids. Surprisingly, this standard did not originate with ISO but rather the National Aerospace Standards (NAS) organization.

To fully understand the ISO 4406 solid contaminant standard, you need to go back to the beginning. 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 you count (or your IoT monitoring system counts for you) in the fluid, according to the cleanliness code developed by the International Organization for Standardization (ISO). When our youngest turned 5, we decided we wanted one more and chose to adopt a fifth child, knowing full well that life would double for us once again. Little did we know that the impact of each additional child would be more of a multiplication factor than simple addition. 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.įast forward a few years, and we had our first four children within five years. Let me explain: 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. Contamination particles are a lot like children.

Iso 4406 particle count