Cleanroom Filters

At Total Clean Air, our core duty is to ensure your cleanroom environment is as clean as possible. Filters are a very critical part of that process, as they are usually the first component at the inlet of most air units. Their purpose is to filter contaminants from the air before it finds its way into the cleanroom.

Filters are found in nearly every industry; the type used will depend on the products manufactured in that particular industry and the degree of purity expected. Products that require extreme levels of purity are manufactured or assembled in cleanrooms with ultra-filtration to achieve just that.

Modular Cleanroom Benefits

  • Modular Construction
  • Quick Assembly Time
  • Versatility
  • Reconfiguration
  • Airflow Control
  • Inexpensive Modifications

Pneumatic Filters

Pneumatic filters or Compressed Air filters are used in cleanrooms or pneumatic devices. They serve to filter contaminants in the form of dust, vapour, water and oil molecules. Pneumatic filters are very important in cleanrooms in order to protect pneumatic devices from harm, caused by contamination. They are usually the first component of air units. The average pneumatic filter removes contaminant particles to an efficiency of 5 µm.

Cleanroom Design, Build & Validation

  • Budgeting and planning
  • Engineering, design & layout
  • Airflow and filtration design
  • Construction and Installation
  • Full Certification of our product
  • Industry-specific equipment installation
  • Validation

Types of Pneumatic Filters

Particulate Filters

Particulate Filtration is the removal of solid particles from a liquid or gas. Particulate compressed air filters are used to remove dust and particles from the compressed air.  It can remove dust particles as little as 1.0 µm and can filter liquid water and oil from the compressed air to an efficiency of 0.1 µm. They are also known as ‘after-filters’ and are usually located after the desiccant air dryer.

Coalescing Filters

Coalescing filters are a type of compressed air filter which removes water, oil and condensed moisture from the compressed air stream. They feature a different design when compared to standard filters. The filter traps and holds these impurities and vapours. Once the vapours become large enough to form droplets, they are then drained off. They can filter particles as little as 0.3 to 0.6 µm.

Activated Carbon Filters

Activated Carbon Filters use carbon materials (charcoal) to remove vapours and hydrocarbon odours from the air. They use a chemical adsorption process to trap contaminant molecules within the carbon substrate. They are mostly used in factories where food is produced.

Primary Filters

Primary filters are able to filter out dust particles as little as 5 µm. They are sometimes used as pre-filters, serving as the first filter in an air unit. Most primary filters make use of particulate filtration to remove dust particles, water and oil molecules from the compressed air, before letting it into the unit.

Secondary Filters

Secondary Filters can extract impurities as little as 50 nm from the compressed air. They are used to increase the efficiency of the filtration process and are sometimes optional. They can remove very fine particles that could not be removed during the primary filtration stage.

HEPA Filters

High Efficiency Particulate Air (HEPA) filters are typically used in ISO Class 5 to ISO Class 8.  They are designed to trap very fine contaminant particles (as low as 0.3 µm) to a minimum efficiency of 99.97%. However, they do not filter out gas or odour molecules. HEPA filters are mainly found in hospital operating rooms, drug manufacturing industries, food and beverage facilities, and semiconductor (chip) companies.

ULPA Filters

Ultra Low Penetration Air (ULPA) filters are mainly used in ISO Class 4 to ISO Class 1. They have a minimum efficiency of 99.9997%, trapping very fine particles (dust, mould, pollen or bacteria) as little as 0.12 µm. ULPA filters are more efficient and costly than HEPA filters.  Its media comprises countless randomly arranged fibres that effectively trap these fine particles. They are mostly used where maximum purity is critical in the making of a product or process. This covers the semiconductor industry and certain drug manufacturing facilities.

Filtration in Cleanrooms

Filtration in cleanrooms usually takes place in three stages. Firstly, compressed air enters the unit and meets the pre-filter. This pre-filter is then used to remove dust particles as little as 5 µm, before allowing the compressed air to pass through. The compressed air meets a secondary filter – usually a HEPA or ULPA filter – with an efficiency that matches the required cleanroom conditions. There is usually an after-filter, a particulate, coalescing or activated carbon filter, which removes water, oil or odour vapour, depending on which type of product is being manufactured in the facility. The filtered air is then allowed into the cleanroom, pure and safe for the product or process.

Filter Testing and Maintenance

It’s necessary to conduct a leak test and filter integrity test on filters periodically. Dispersed Oil Particulate (DOP) testing can be carried out to check the integrity of ULPA and HEPA filters. This involves introducing particles into the filter unit and measuring the output. As pressure drop increases around a HEPA or ULPA filter, its integrity becomes compromised. It is therefore recommended that the filter be inspected and changed periodically to maintain the purity of the cleanroom.

Contact Us

Total Clean Air can provide standard filters that match the required efficiency of your cleanroom. Our engineers are CTCB-I certified to undertake stringent integrity tests on your filters and replace them appropriately wherever necessary. Contact us today to test or replace your filters for assured efficiency and protection.

Phillip Godden

Phillip Godden is the Founder & Chief/Executive Officer at Total Clean Air.

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