Common sense about the Air Filter for Dust-free Workshops and Clean Rooms
Classification of air filter
There are many kinds of cleanroom air filter. Classified by structural form, they include:
- Panel-type air filter
- Folding-type air filter
- Bag-type air filter
- Folding-type air filter with partition
- Folding-type air filter without partition
Classifying by filtration efficiency is the most common method:
- Primary efficiency air filter
- Middle efficiency air filter
- High efficiency air filter
- Sub-HEPA air filter
- HEPA air filter/ULPA air filter
Selection and configuration of air filters
- For small-scale equipment such as clean benches, air showers, and laminar flow hoods, due to their low airflow volume, the fresh air Inlet typically uses primary filters or medium efficiency filters, while the air supply outlet must use HEPA filters or ULPA filters.
- In the selection and configuration of air filters for purification HVAC systems, it is generally based on the air cleanliness class of the cleanroom and the specific requirements of the production process to carry out rational selection and configuration.
- For Class 1,000 to Class 100,000 cleanroom systems, a three-stage air filtration configuration is typically adopted, including primary, medium, and high-efficiency filters; the primary and medium filters are generally installed in the air handling unit, with the medium filter positioned in the positive pressure section, while the sub-high-efficiency or high-efficiency filters are typically located at the terminal end of the HVAC system.
- For Class 100 to Class 1,000 HVAC systems, primary, medium efficiency, and sub-HEPA filters are typically installed in the fresh air handling unit. Meanwhile, the HEPA /ULPA air filter is adopted in the cleanroom air circulation system. The HEPA /ULPA filters are positioned at the terminal end of the purification HVAC system on the cleanroom ceiling—to ensure compliance with the required air cleanliness class.
- When the total airflow volume of the purification system is known, the number of required filters can be determined based on the rated airflow capacity of the selected filters.
liquid tank type filters
air filters
Application and filtration range
- Primary efficiency air filter
It is mainly used as a pre-filter at the fresh air inlet of the air conditioning system to intercept large-sized particles in the atmosphere. The filtering objects are suspended particles larger than 5μm and sedimentary particles larger than 10μm, as well as various foreign matters, to prevent them from entering the system. The filter material is generally spray-bonded cotton, polyester non-woven fabric, and polypropylene fiber. Its filtration efficiency is based on the filtration of particles ≥ 5μm.
- Middle efficiency air filter
Because it has a pre-filter in front that traps large particles, it can be used as the final filter in a general air conditioning system and as a pre-filter for medium and high-efficiency filters in a clean air conditioning system. The filter material is generally polyester non-woven fabric, polypropylene fiber, or glass fiber. It is mainly used to trap suspended particles of 1-10 μm, and its efficiency is determined by filtering particles ≥ 1 μm.
- High efficiency air filter
It can be used as the terminal filter for general purification systems or as an intermediate filter for high-efficiency filters. The filter material is generally made of polyester non-woven fabric, polypropylene fiber, or glass fiber. It is mainly used to retain particles of 1-5 μm, and the efficiency is based on the filtration of particles ≥ 1 μm.
- Sub-HEPA air filter
It is mainly used as the end filter of the clean room, and can also be used as the pre-filter of the high-efficiency filter and the final filter of the fresh air system to improve the quality of the fresh air. The filter material is generally polypropylene fiber or glass fiber. It is mainly used to retain particles smaller than 1 μm, and the efficiency is measured by filtering particles with a diameter of ≥ 0.5 μm.
- HEPA air filter/ULPA air filter
The main component is the end filter of the clean room, which is designed to ensure the attainment of various cleanliness levels.
Its efficiency is measured by the filtration of particles ≥ 0.5 μm. The filter material is typically ultra-fine glass fibers.
HEPA filters
bag-type filters
Suzhou Pharma Machinery Co.,Ltd.
2026/01/14
Tia
