The WATER FILTERS of the QC program are made to prevent build-up of particulates. These filters should NOT allow particles larger than ______ microns to pass.

• A. 50 microns
• B. 10 microns
• C. 25 microns
• D. 100 microns

Answer: (C)

Filtration micron rating defines what size particles the filter can block. If a filter should prevent buildup of particulates, you want it to stop particles above a certain size while letting smaller ones pass. In this QC water system, the specified cutoff is 25 microns, so particles larger than 25 microns are blocked and won't pass through. A 50- or 100-micron filter would let bigger particles through, risking clogging and buildup. A 10-micron filter would block smaller particles too, potentially causing unnecessary flow restrictions and clogging in normal operation, beyond what this QA program requires. Therefore 25 microns is the correct rating.