Statistics show that the dust concentration in rural areas is about 100000 particles/liter, in suburban areas it is about 200000 particles/liter, in cities it is about 300000 particles/liter, and in heavily polluted areas it can reach over 1 million particles/liter.
So how does an air filter capture dust particles during operation? Air filtration technology mainly adopts a filtration separation method: by setting different performance filters, suspended dust particles and microorganisms in the air are removed, that is, dust particles are captured and retained through filter media to ensure the cleanliness requirements of the incoming air volume. The filter material used is fine diameter fibers, which can not only facilitate the smooth passage of airflow but also capture dust particles.
The dust filtered by clean technology is generally 0.1-10 μ The dust particles of m have a smaller particle size and contain both solid and liquid particles; The suspended organic particles in the atmosphere include microorganisms, plant pollen, flocs, and hairs. Microorganisms generally include viruses, rickettsia, bacteria, fungi, protozoa, and algae. The main control measures for air purification are bacteria, fungi, and viruses. Because microorganisms mainly adhere to dust particles, controlling the dust particles in the air can also effectively control bacteria, fungi, and viruses in the air. To achieve this, it is necessary to filter through a particulate filter with barrier properties. Generally, the filtration efficiency of ordinary high-efficiency filters for bacteria can reach 99.996%, which can basically meet the filtration and purification requirements of biological cleanrooms.
There are five main types of dust particles captured by air filters during operation:
1. Interception effect: When a particle of a certain size moves near the fiber surface, the distance from the centerline to the fiber surface is less than the particle radius, and dust particles will be intercepted and deposited by the filter material fibers.
2. Inertia effect: When the particle mass or velocity is large, it collides with the fiber surface due to inertia and deposits.
3. Diffusion effect: Small particle sizes have strong Brownian motion and are prone to colliding with fiber surfaces.
4. Gravity effect: When particles pass through the fiber layer, they settle on the fiber due to gravity.
5. Electrostatic effect: Both fibers and particles may carry charges, creating an electrostatic effect that attracts particles to the surface of the fibers.
As more and more dust is captured, the filtration efficiency of the filter layer also decreases while the resistance increases; When the resistance value or efficiency drops to a certain value, the filter needs to be replaced in a timely manner to ensure the requirements of purification cleanliness.