Since 1953, Liberty Industries has been creating high quality cleanrooms, cleanroom filtration systems, and contamination control supplies. We have more than 65 years of experience designing and building customized cleanrooms for use in a diverse range of industries by customers around the world.
The filtration system is a critical component of any cleanroom. Well-designed cleanrooms require air filters that control air flow, remove particles from the room, and keep external pollutants out to prevent contamination of manufacturing processes, critical research or other projects.
Understanding the basics about cleanroom filtration can help to avoid contamination and ensure that the cleanroom is functioning at an optimal level. Here are five important facts:
1. There are three types of air filters.
- Pre-filters. These filters pre-remove larger particles from the air before the it reaches more comprehensive HEPA or ULPA filters, extending the lifespan of the more expensive filters.
- HEPA filters. High-Efficiency Particulate Air (HEPA) filters are the most commonly used filter, with capabilities to filter particles of 0.3µm or larger. Depending on the application, HEPA filters can last more than seven years before replacement is required in many applications. Based on specific cleanroom protocol, filters may have to be changed more often.
- ULPA filters. 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. Particles may be filtered in numerous ways due to a filter’s design
Depending on the design of the filter, 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. 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 commonly employed filter in cleanrooms.
HEPA filters were first invented in 1941 to protect scientists from Alpha particles created as they developed the atomic bomb. They are made from pleated layers of media paper, in which particles then get trapped. Filters must remove a minimum of 99.97% of particles before they can be designated as HEPA.
4. Filter maintenance should be performed regularly depending on the filter.
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 these maintenance schedules.
5. People are the biggest risk to proper cleanroom filtration.
While filters keep air filtered, humans pose the biggest risk 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 also incorporate sinks, showers, and other disinfection equipment in entry and/or exit areas for applications with very high cleanliness standards.
Filtration Products Available at Liberty Industries
We offer a wide range of quality filtration products to suit every need. Some of our most popular products include:
- HEPA/ULPA filters. Our filters are engineered to meet ISO 14644-1.
- Pre-filters. These non-woven, fine-fibered media pre-filters allow you to upgrade preexisting systems easily.
- Charcoal filters. Charcoal filters used primarily for odor reduction.
Implementing a high-quality filtration system is vital to the functionality of any cleanroom. To learn more about how our experts can help you design or optimize your cleanroom, contact us or request a quote today.