NAS 1638 is comprised of fluid cleanliness classes, each class defined in terms of maximum allowed particle counts for designated particle size ranges. It is used widely in the UK North Sea industries. Another change involved the addition of a third scale. The NAS 1638 cleanliness standard was originally developed for aerospace components in the US but is still widely used for industrial and aerospace fluid power applications. Tables 3(a) and 3(b) provide a comparison of ISO scale numbers under ISO 44:1999, respectively. The table below shows the classification values that may still be in use for older specifications based on Hiac particle counters. The following table shows a cumulative measurement result of an oil that contains.
The classes refer to maximum number the particles in 100mL in different size classes. Particle measurements as per ISO 4406:2017 are usually displayed as a.
#ISO 4406 TABLE FULL#
The full table of ranges for ISO 4406 is shown below NAS 1638 is an older standard developed in 1964 to define classes of contamination in aircraft components and hydraulic fluids. The work of preparing International Standards is normally carried out through ISO technical committees. Using the table below, we can see a cleanliness rating of 18/16/13 would mean that there wereġ300 - 2500 particles greater than 2 micron in sizeģ20 - 640 particles greater than 5 micron in size, andĤ0 - 80 particles greater than 15 microns in size. ISO/FDIS 4406:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). Although there is no guidance given in the standard on. The NAS 1638 coding system defines the maximum numbers permitted of 100mL volume at various size intervals (differential counts) rather than using cumulative counts as in ISO 4406.
#ISO 4406 TABLE CODE#
However some manufacturers have expanded the code to three numbers by the addition of a code number representing the number of particles greater than 2 µm, e.g. It is still referred to in some industries, although the ISO 4406 cleanliness codes are more commonly found.
16/13, based on the number of particles greater than 5 µm and 15 µm respectively in a known volume of fluid. Under ISO 4406 cleanliness is classified by a two number code, e.g. The ISO Cleanliness Code, ISO 4406, 1987 is the perhaps the most widely used International standard for representing the contamination level of industrial fluid power systems.