Box-type filters (also known as box-type high-efficiency / medium-efficiency filters, plate-type box filters) mainly utilize the interception, adsorption, diffusion, and electrostatic effects of the filter medium to block dust and particles in the air onto the surface or inside the filter material, thereby outputting clean air. The overall structure consists of a box body, filter material (non-woven fabric, glass fiber filter paper, PTFE membrane, etc.), guard net, and sealing rubber strip. The airflow passes through the box body in a straight line to complete the filtration.
I. Basic Structure
It mainly consists of: metal outer frame box body, filter material (non-woven fabric, glass fiber filter paper, PTFE membrane, etc.), guard net, and sealing rubber strip. It is made into a square box body shape, which is convenient for installation in air conditioning units, fresh air cabinets, and purification equipment.
II. Core Filtration Principles (4 Functions)
Inertial collision: Large particles of dust move with the airflow and cannot turn when encountering fibers, directly colliding with the fibers and being retained. Mainly filters dust particles larger than 1 μm.
Interception effect: Medium-sized particles are close to the fibers and are directly caught and blocked by the fibers, achieving physical interception.
Brown diffusion: Small particles (0.1–1 μm) move randomly in Brownian motion, collide with the fibers and are adsorbed, which is the key to filtering fine dust in high-efficiency box-type filters.
Electrostatic adsorption: The filter material has its own static electricity, adsorbing charged tiny dust particles, improving the efficiency of capturing fine particles.
III. Complete Working Process
Dusty air is driven by the fan and enters the box body;
The airflow passes through the filter material evenly, and the dust is intercepted and adsorbed on the surface and deep layer of the filter material;
The filtered clean air flows out from the outlet surface;
Dust accumulates continuously, and the pressure difference increases. When it reaches the limit, the filter is replaced.
IV. Simple Distinction
Medium-efficiency box-type: The filter material is mostly non-woven fabric, filtering dust particles of 1–10 μm, used for intermediate filtration in air conditioning systems;
High-efficiency box-type: Glass fiber filter paper / PTFE, filtering fine dust particles of 0.3 μm, used for the end of clean rooms, and for exhaust / supply air of precision equipment.
