This part of ISO 16232 describes the principles of extraction of contaminants by test on a laboratory functional test bench with the test liquid flowing under pressure or under vacuum. It is applicable to both active and passive components through which the fluid can easily flow. Unless otherwise specified, this part of ISO 16232 deals with particulate contamination only. It does not, therefore, cover appearance defects or contamination by liquid or gaseous materials. It covers the amount and the nature of residual particles resulting from manufacturing processes and from the environment.