As the first line of defense in air purification systems, pre-filters (commonly G3-G4 grade) are widely used in workshop fresh air systems, central air conditioners, and purification equipment pre-treatment. They capture large particles like dust, hair, and fibers above 5μm, protecting downstream medium-efficiency, high-efficiency filters and fans.

Delayed replacement causes soaring resistance (from initial 50-150Pa to over 250Pa), increasing fan energy consumption by 15%-30%. It also leads to filtration failure—blocked pores let contaminants pass through, cutting the lifespan of downstream equipment by over 50%. In humid environments, excessive dust buildup breeds bacteria; airflow may even dislodge dust, causing secondary pollution.

Replace pre-filters based on fixed cycles + actual conditions:

1.Pressure difference trigger: Replace immediately when resistance reaches 2-3 times the initial value (e.g., 160-240Pa for 80Pa initial resistance) or exceeds the 250Pa industry threshold.

2.Visual inspection: Replace if dust buildup exceeds 2mm, filter media turns dark gray/black, or shows stains/oil marks that don’t clear with gentle tapping.

3.System anomalies: Replace first (after ruling out pipe blockages and fan malfunctions) if air supply drops over 20%, or fan noise/energy consumption rises significantly.