System Cleanliness – Ratings & Filtration
In order to monitor and quantify the cleanliness of the fluid in an hydraulic system, standard rating systems have been developed over the years. These cleanliness ratings also allow us to measure the effectiveness of any filtration systems put in place to maintain the cleanliness of an hydraulic system. Cleanliness Rating Systems The cleanliness of a fluid can be measuring using a number of different standard classification systems, as outlined below. ISO 4406 ISO 4406 describes a method by which to count and record particle sizes. An average is taken by counting three size ranges. Particles greater than 4 microns. Particles greater than 6 microns. Particles greater than 14 microns. Because the number of particles within a system may be very high, the actual number is not used. Instead, a number is used to represent the value. This "class" number is based on the following table. The table below is the ISO 4406 codes. There has been two major editions of this standard, 1987 and 1999. 1999 is the current edition, and it should be used when possible. ISO 4406: ...