HEPA / ULPA Quantity Design Guidelines
For the Semiconductor/Auto/Electronic/Mems/industries:
| Filtration Classification | Quantities and Percentage of Coverage |
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| Fed 209E English | Fed 209E Metric | ISO 14644-01 | Recommended Percent of HEPA/ULPA Ceiling Coverage |
| 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 are 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.
For the Medical Device/Bio Sciences/Pharma
Existing Condition |
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| Room Air Changes Per hour | Max # of 2x4 opening | 376 | |||
| Length | Percent Coverage | 12% | |||
| Width | HEPA Filters needed | 46 | |||
| Height | CFM per HEPA | 526 | |||
| Filter face velocity | Estimated Watts per FFU 95 | ||||
| Face Area of each HEPA | |||||
| Energy Cost ($/kWh) | 0.12 | ||||
| Hours of operation per year | 8760 | ||||
| Condition with ceiling at 10 foot | |||||
| Room At Changes Per hour | 25 | Max # of 2x4 opening | 975 | ||
| Length | 94 | Percent Coverage | 6% | ||
| Width | 83 | HEPA Filters needed | 59 | ||
| Height | 9.5 | CFM per HEPA | 650 | ||
| Filter face velocity | 73 | ||||
| Face Area of each HEPA | 7.2 | ||||
| Energy Cost ($/kWh) | 0.12 | ||||
| Hours of operation per year | 8760 | ||||
| Condition with ceiling at 9.5 foot with same number of FFU | |||||
| Room At Changes Per hour | 59 | Max # of 2x4 opening | 376 | ||
| Length | 51 | Percent Coverage | 12% | ||
| Width | 59 | HEPA Filters needed | 46 | ||
| Height | 9.5 | CFM per HEPA | 610 | ||
| Filter face velocity | 85 | Estimated Watts per FFU 115 | |||
| Face Area of each HEPA | 7.2 | ||||
| Energy Cost ($/kWh) | 0.12 | ||||
| Hours of operation per year | 8760 | ||||
When designing the HEPA/ULPA location, you must be cognizant of the room furniture and equipment/tool layout. As this will drastically affect the fluid dynamics of the room and may create grey zones and migrating of particles into dead zones. It will also affect the flow to the low air wall returns or diminish the raised floor capability to pull air evenly throughout the cleanroom.
The arrangement and spacing of the HEPA/ULPA filters are the MOST important aspect of the cleanroom/Lab design. It can make the room fail in testing or worse yet, it will pass but have areas where your product gets contaminated unbeknownst to you until it is too late.