Clean Room Filter: Amazing Things You Don't Know About
- 17, 03, 2021
One of the most essential components of any cleanrooms is the air filtration system. In a well-designed cleanroom, air filters control airflow, prevent particles from entering clean room and contaminating manufacturing processes, research and other projects.
Understanding the basics about clean room filter can help avoid contamination and ensure that the cleanroom is functioning optimally. In this article, VCR will provide you amazing things about clean room filters
1. According to filtration efficiency, there are 4 types of air filters
- Pre-filter (Coarse filter): These filters remove larger particles from the air before it reaches more comprehensive HEPA or ULPA filters, extending the lifespan of the more expensive filters.
- Fine filter: The filters remove small particles from the air after they reach the coarse filter. The filter efficiency of fine filter is higher than that of coarse filter.
- HEPA filter: High-Efficiency Particulate Air (HEPA) filters are the most commonly used filter, with capability to filter particles of 0.3µm or larger. Depending on the application, HEPA filters can last over seven years before replacement is required in many applications. Filters may need to be changed more often on the basis of a specific cleanroom protocol.
- ULPA filter: Ultra Low Particulate Air (ULPA) filters are similar to HEPA filters, though they are capable of removing 99.999% of contaminants larger than 0.12µm. This capability to remove smaller particles makes ULPA filters the most expensive filter type.
2. Depending on the filter design, the particles are filtered in numerous ways
There are four different ways particles may be filtered:
- Straining/sieving. This filtering method catches any particles that are larger than the clearance between the fibers of the filter.
- Inertial/impaction: The inertia of the particles forces them out of the airstream, where they get stuck to adhesive fibers.
- Interception: Smaller particles get caught in the airstream and are carried towards the filter fiber, which then intercepts them before they can be released back into the air.
- Diffusion: This method is perfect for very small particles, diffusion bombards contaminant particles with air molecules until they go into vibration mode. This vibration makes it much easier for filter fibers to catch even the smallest particles, although it has little impact on larger ones.
3. HEPA filters are the most widely-used filter in cleanrooms
HEPA filters were first invented in 1941 to protect scientists against Alpha particles, created during their atomic bomb development. HEPA filters are made from pleated layers of media paper, in which particles then get trapped. Filters shall remove, before they can be designated as HEPA, a minimum of 99.97 percent of particles.
4. The air filters maintenance should be performed regularly
Since filters for cleanrooms can be used 24/7, they may deteriorate faster than other types of equipment. On average, pre-filters should be replaced six times a year and HEPA filters should be replaced every three years. However, factors such as cleanroom location, nearby construction, and air pollution can impact air filter maintenance schedules.
5. Personnel is the primary threat to clean room air filters
While filters keep air filtered, humans pose a dangerous threat to cleanroom filtration. It is the responsibility of the employee to reduce the risk of contamination and ensure that the air is being properly filtered. Proper clothing such as gowns, coveralls, gloves, face masks, and goggles can help prevent contamination from employees. Cleanrooms may include sinks, showers, and other disinfection equipment in entry and/or exit areas for applications with very high cleanliness standards.
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