How does a purification air conditioning treatment unit achieve efficient air purification through a multi-stage filtration system?
Publish Time: 2025-09-11
In environments with extremely stringent air quality requirements, such as pharmaceuticals, biological laboratories, hospital operating rooms, semiconductor manufacturing, and food processing, airborne particulates, bacteria, viruses, volatile organic compounds, and dust can directly impact product quality, experimental results, and even personnel health. To address this challenge, the purification air conditioning treatment unit, a core component of cleanroom environments, is widely used in various high-purity environments. Its key advantage lies in its multi-stage filtration system, which efficiently removes airborne contaminants through layer-by-layer interception and graded purification.
1. Primary Filtration: Intercepting Large Particles and Protecting Subsequent Equipment
The first line of defense in multi-stage filtration is the primary filter, typically made of washable nylon mesh or disposable non-woven fabric. It is installed at the fresh air inlet or mixing section of the unit. Its primary function is to capture coarse airborne particles larger than 5μm in diameter, such as dust, hair, pollen, and insect fragments. This not only significantly improves the air quality entering the unit, but more importantly, protects the medium-efficiency and high-efficiency filters, preventing premature clogging and shortening their service life, thereby reducing maintenance costs. The primary filter has a short replacement cycle and low cost, acting as the "front-end barrier" for the entire purification system.
2. Medium-efficiency Filtration: Further Removal of Medium-Sized Particles
After primary filtration, air enters the medium-efficiency filter, typically a bag or plate type, using synthetic or glass fiber as filter media. The medium-efficiency filter effectively intercepts fine particles ranging from 1–5 μm, such as smoke, mold spores, and some bacterial vectors. The filtration efficiency at this stage can reach over 80%–90%, significantly reducing the burden on the final high-efficiency filter and extending its service life. Medium-efficiency filtration is often installed after the fan section to ensure internal cleanliness of the air supply system and prevent dust accumulation on the fan from affecting performance.
The final and most critical step in air purification is the high-efficiency (HEPA) or ultra-high-efficiency (ULPA) filter, typically installed at the end of the air supply section or in the static plenum within the cleanroom. HEPA filters have a filtration efficiency of at least 99.97% for particles 0.3μm, while ULPA filters achieve a filtration efficiency of over 99.999% for particles 0.12μm. These filters utilize ultrafine glass fibers or polypropylene meltblown materials to virtually completely remove microorganisms, viral aerosols, submicron dust, and smoke particles from the air through a variety of mechanisms, including interception, inertial collision, diffusion, and electrostatic adsorption. In pharmaceutical sterile workshops and Class 100/Class 1000 cleanrooms, HEPA filters are crucial components for ensuring environmental cleanliness standards are met.
4. Auxiliary Purification Technologies: Addressing Special Pollutants
In addition to particulate matter, some applications also require the treatment of gaseous pollutants. Therefore, purification air conditioning treatment units often incorporate activated carbon or chemical filters to absorb VOCs such as formaldehyde, benzene, ozone, acid and alkaline gases, and odors. Some high-end units also feature ultraviolet germicidal (UV-C) lamps, installed near the surface cooler or filter, to kill bacteria and mold attached to moist surfaces and prevent microbial growth. In addition, photocatalytic oxidation (PCO) or plasma technology is also used to decompose organic pollutants and improve air quality.
5. Airflow Organization and Sealing Design Ensure Filtration Effectiveness
An efficient filtration system requires effective airflow organization and a strict sealing structure. The purification air conditioning unit utilizes a negative pressure design or a fully enclosed double-panel enclosure to ensure that all air is filtered before being discharged, eliminating bypass air leakage. Variable frequency fan control ensures stable air volume, preventing fluctuations in air speed from affecting filtration efficiency. Furthermore, the filter mounting frame utilizes a knife-edge seal or liquid tank seal to ensure leak-free operation, meeting the stringent airtightness requirements of cleanrooms.
6. Intelligent Monitoring and Maintenance Alerts
The purification air conditioning treatment unit is equipped with a differential pressure sensor that monitors the resistance changes of each filter stage in real time. When the differential pressure exceeds the specified value, an automatic alarm is issued, prompting filter element replacement, ensuring that the system is always in optimal operating condition.
The purification air conditioning treatment unit utilizes a three-stage progressive filtration system (primary-mid-high efficiency) combined with auxiliary purification technologies and precise airflow control to form a complete air purification chain. It can not only effectively remove all kinds of impurities in the air from coarse particles to nano-scale pollutants, but also operate stably for a long time to meet the needs of high-standard clean environment.
