A

abrasive particles:

particle liable to change the surface finish

active component:

component that may induce circulation in the fluid or may be activated by the fluid circulation during operation
for instance: cylinder, injector, pump, valve, ...

agglomerate:

assembly of two or more particles which are in intimate contact and cannot be seperated by stirring

ambient contamination:

contaminants that are found in the atmosphere surrounding the component originating from the atmosphere, operators or from objects in contact with the component

APC:

automatic light extinction particle counter