Filters play a critical role in the cleanrooms for a number of reasons, and the top listed is the control of particle count. We are well aware that cleanrooms are required for the manufacturing of drug products and sensitive electronic components, where prevention of contamination is the basic requirement.
To maintain the cleanroom status, various types of filters are installed in the heating, ventilation and air conditioning system (HVAC), including pre-filters, bag filters ,EPA filters ,HEPA filters and ULPA filters.
HEPA and ULPA filters are the last line of defence against viable and non-viable particles count, so in this article, we will learn the basic difference between HEPA filters and ULPA filters.
HEPA Filters
- HEPA is an abbreviation of high-efficiency particulate air filters.
- HEPA filters are used in pharmaceutical industries to maintain the status of cleanrooms of ISO class 5,6,7, and ISO 8.
- The pore size of HEPA filters is 0.3 microns and can remove particles of size 0.3 microns and above.
- HEPA filters are 99.97% to 99.99% efficient for removing particles of size 0.3 microns and above.
- HEPA filters are made of small, randomly arranged strands of borosilicate glass microfibers.
- There are two types of HEPA filters, H13 and H14.
- The pressure drop through HEPA filters is less than ULPA filters, where air changes per hr are reduced for the same size filter due to pressure drop.
- The HVAC system where HEPA filters are installed consumes less energy.
- The lifespan of HEPA filters is up to 10 years, depending on their usage and the efficiency of pre-filters.
- The HEPA filter cost is less than ULPA filters.
ULPA Filters
- ULPA is an abbreviation of ultra-low particulate air filters.
- ULPA filter requirements are high for cleanrooms where sensitive micro electronic components & semiconductors are manufactured or assembled including ISO class 3.
- The pore size of ULPA filters is 0.12 microns and can remove particles of size 0.12 microns and above.
- ULPA filters are 99.999% efficient for removing particles of size 0.12 micron and above.
- ULPA filters are also made of small, randomly arranged strands of borosilicate glass microfiber, but these microfibers are denser as compared to the HEPA filters.
- There are two types of ULPA filters, U15, U16 and U17.
- Due to the denser media of ULPA filters, the air pressure drops up to 50% as compared to the HEPA filter of the same dimensions, so air changes per hr are also less than HEPA filters of same size.To get same air changes per hr we have to increase the size of ULPA filter.
- The HVAC system where ULPA filters are installed consume more energy.
- The lifespan of ULPA filters is 5 to 8 years.
- ULPA Filters are costly compared to HEPA filters.
Conclusion
HEPA & ULPA both are used in cleanrooms with certain advantages and limitations.HEPA filter usage is high compared to the ULPA filters, and these are also less expensive.
One thing which is common for both HEPA & ULPA filters is that both can’t remove smell, odour, fumes & gases.
Also Read