Performance Comparison and Applications of Panel Prefilters and Medium-Efficiency Filters in Air Filtration Equipment

Basic Performance Comparison

Performance parameter | Panel prefilter | Medium-efficiency filter

Efficiency grade | Under GB/T 14295-2019: G1, ≥20%; G2, ≥35%; G3, ≥65%; and G4, ≥85%, targeting large particles ≥5 μm such as dust, hair, and fibers | Under GB/T 14295-2019: F5, ≥40%; F6, ≥60%; F7, ≥80%; F8, ≥90%; and F9, ≥95%, targeting particles from 0.5 to 5 μm such as pollen, smoke, and fine dust

Initial pressure drop at rated airflow | 30–80 Pa; for example, approximately 50 Pa for a G4 filter at 320 m³/h | 80–150 Pa; for example, approximately 120 Pa for an F8 filter at 1,000 m³/h

Dust-holding capacity | Relatively low, 100–300 g/m²; approximately 200 g/m² for a typical G4 filter | Relatively high, 300–800 g/m²; approximately 500 g/m² for a typical F8 filter

Media and construction | Nonwoven fabric, metal mesh, and similar materials in a panel structure 15–50 mm thick | Ultrafine glass fiber or synthetic fiber, mainly in a bag structure 200–400 mm deep

Rated airflow | 100–800 m³/h per unit; for example, approximately 500 m³/h for a 592 × 592 × 46 mm model | 500–3,000 m³/h per unit; for example, approximately 1,500 m³/h for a 592 × 592 × 292 mm bag filter

Replacement interval | 1–3 months and shorter where dust concentration is high | 3–6 months, depending strongly on prefilter performance; better prefilter protection extends the interval

Application Comparison

1. Principal Applications of Panel Prefilters

Front-End Prefiltration in Ventilation Systems

• As the first line of defense in air-conditioning and fresh-air systems, a panel prefilter captures large particles such as dust, hair, and fibers. It protects downstream medium- and high-efficiency filters as well as HVAC components such as heat exchangers and fans, extending their service life.

• Typical applications include central HVAC systems in office buildings, shopping malls, hotels, and ordinary residential buildings.

Coarse Filtration in Industrial Environments

• In dusty workshops and warehouses, it reduces wear on production equipment caused by large particles. Examples include filtration at ventilation inlets in textile mills, machine shops, and printing plants.

Simple Cleanliness Requirements

• Where very high cleanliness is unnecessary, it can serve directly as the final filter to reduce visible airborne dust. Examples include ordinary offices, meeting rooms, and cafeterias.

2. Principal Applications of Medium-Efficiency Filters

Intermediate Filtration Stage

• Installed after the prefilter and before the HEPA filter, a medium-efficiency filter captures additional particles from 0.5 to 5 μm, including smoke, pollen, and bacterial spores. It reduces the HEPA filter's load and is therefore a key stage in extending HEPA service life.

• Typical applications include general hospital wards, non-sterile laboratories, general production areas in electronics factories, and raw-material areas in food-processing plants.

Locations with Moderate Cleanliness Requirements

• A medium-efficiency filter suits areas requiring controlled air cleanliness but not sterile conditions. Examples include outer-packaging workshops in pharmaceutical plants, batching rooms in cosmetics factories, pretreatment areas in automotive paint shops, sports arenas, and exhibition halls.

Supplemental Filtration in Specialized Environments

• In industrial environments with moderate dust concentration, it can serve as the final stage for basic cleanliness. Examples include precision-instrument workshops that are not ultra-clean and libraries where paper dust must be controlled.

Conclusion

Panel prefilters emphasize coarse filtration, low cost, and easy replacement and serve as the system's first barrier. Medium-efficiency filters focus on capturing finer particles and provide the connecting stage between coarse and high-efficiency filtration. The two are normally used together in either a prefilter–medium-efficiency–HEPA sequence or a prefilter–medium-efficiency sequence. This staged approach maintains filtration performance while reducing total operating cost.