A measurement of solid contamination made with an automatic optical counter that sizes particles by light blockage, or with a pore-blockage instrument for dark or wet oils. Results come as particles per mL in size bands such as 4, 6, 14, 21, 38 and 70 microns and feed the ISO cleanliness code. Optical counters read water droplets and air bubbles as particles, so a wet or foamy sample gives a falsely high count.
Particle count spiked overnight on the press, check whether somebody changed an element and left the bypass open.
If small-particle counts jump while the 14 micron number holds steady, suspect water droplets or air bubbles before dirt.
Also heard as
- PC
- particle counting
Related terms
ISO cleanliness code
Three-number code for how many particles above 4, 6 and 14 microns are in a millilitre of fluid.
Oil analysis
Lab testing of in-service oil samples to judge oil condition, contamination and machine wear.
Abrasive wear
Wear caused by hard particles or hard surface peaks plowing and cutting through a softer surface.
Analytical ferrography
Microscope study of wear particles pulled from oil by a magnet, used to identify how a machine is wearing.