The Interception Effect in Air Filtration

Core Principle

The interception effect in air filters is one of the primary filtration mechanisms for small and medium-sized particles. It captures particles mainly through surface contact with filter fibers.

Core Principle

When airflow carrying particles moves parallel to the filter fibers, some particles have too little inertia to undergo inertial impaction and instead follow the airflow close to the fiber surface. If a particle's radius is greater than the shortest distance between the airflow streamline and the fiber surface, the particle brushes against and adheres to the fiber—as if it were too large to pass—thereby achieving filtration.

Key Characteristics

Target particles: This mechanism primarily captures particles measuring 0.1–1 μm, such as certain dust particles, smoke particles, and fine pollen. Particles in this size range have too little inertia to be captured through inertial impaction, yet are relatively too large to readily contact fibers through random diffusion.

Factors Affecting Performance

Filter-fiber spacing: The denser the fibers and the smaller the gaps between them, the stronger the interception effect.

Particle radius: Larger particles are more likely to extend beyond the safe distance between the airflow and the fiber, increasing the probability of interception.

Airflow velocity: Speeds that are too low or too high can reduce performance. At a moderate velocity, particles are more likely to travel close to the fiber surface and be intercepted steadily.

In practical filtration, interception works together with inertial impaction, diffusion, and other mechanisms to improve a filter's overall efficiency across a range of particle sizes.

Key Characteristics

Target particles: This mechanism primarily captures particles measuring 0.1–1 μm, such as certain dust particles, smoke particles, and fine pollen. Particles in this size range have too little inertia to be captured through inertial impaction, yet are relatively too large to readily contact fibers through random diffusion.

Factors Affecting Performance

Filter-fiber spacing: The denser the fibers and the smaller the gaps between them, the stronger the interception effect.

Particle radius: Larger particles are more likely to extend beyond the safe distance between the airflow and the fiber, increasing the probability of interception.

Airflow velocity: Speeds that are too low or too high can reduce performance. At a moderate velocity, particles are more likely to travel close to the fiber surface and be intercepted steadily.