Cleanroom Construction Design Guidelines


Filtration Classification Quantities and Percentage
of Coverage
Fed 209E English Fed 209E Metric ISO 14644-01 Recommended Percent
of HEPA/ULPA Ceiling
Class 100,000 M6.5 Class 8 4% diffused air
Class 10,000 M5.5 Class 7 10% recommended diffused air
Class 1,000 M4.5 Class 6 27% recommended laminar flow air
Class 100 M3.5 Class 5 54% laminar flow air
Class 10 M2.5 Class 4 90% laminar flow air
Class 1 M1.5 Class 3 100% laminar flow air

Ceiling Coverage Calculations

To determine the recommended ceiling coverage required with 2′ x 4′ HEPA’s or ULPA’s divide the square foot of the cleanroom by eight (2′ x 4′) then multiply the recommended percentage and that will provide you with the quantity of units needed.
Note: The recommended quantities are for reference only. They are based on optimum room layout and design to obtain certain class cleanrooms with the minimal amount spent on filtration. The arrangement and spacing of filtration is one of the most crucial characteristics of cleanroom design. Equipment layout, return air grills and personnel have profound impact to the fluid dynamics of the room. Cleanroom protocol and maintenance also are key factors in ensuring constant contamination control to desired specifications.