18. What are The Characteristics and Working Principle of Glass Fiber Material in Filtration?
The Characteristics of Glass Fiber Material in Filtration:
Glass fiber can effectively separate lubricating oil droplets with diameters ranging from 50 to 0.01 μm. It does not require adsorption or absorption during the filtration process, making it highly efficient and superior to other materials.
Working Principle of Glass Fiber Material in Filtration:
Air flows into the middle of the filter, and oil droplets are collected through four mechanisms: gravity settling, inertial impaction, direct interception, and diffusion.
1. Gravity Settling: When the airflow velocity inside the filter is low, oil droplets with a diameter of 20 to 50 μm are mostly collected through free-fall due to gravity before reaching the filter media. The airflow continues to carry them down as it passes through the filter media, and the efficiency decreases with increasing airflow velocity.
2. Inertial Impaction: Suspended particles with diameters larger than 1 μm have considerable mass and tend to collide with the fiber layers due to their inertia when their path deviates from the airflow direction. Higher airflow velocity leads to a higher collision rate.
3. Direct Interception: Particles with diameters ranging from 0.3 to 1 μm are carried along with the airflow and are intercepted and separated by the fiber layers at about 1/2 of the filter depth. Smaller particles have a lower interception rate.
4. Diffusion: Particles with diameters smaller than 0.3 μm have such small mass that they no longer exhibit typical liquid behavior. They undergo random Brownian motion, which is inconsistent with the airflow direction. This Brownian motion allows them to be captured by finer filter layers. Smaller particles exhibit more intense Brownian motion, increasing their chances of capture.