Related Technical Factors Determining The Dust Holding Capacity Of High-efficiency Air Filters

The technical factors that determine the dust holding capacity of high-efficiency air filters can be vividly understood as: the dust holding capacity is like the storage capacity of a "warehouse", and its size is determined by the space of the warehouse itself (filter materials and structure), the stacking method of goods (fiber structure and filtration mechanism), and management rules (setting of resistance endpoints).
The following are the four core technological dimensions that determine the dust holding capacity:

• Filter material type: The dust holding capacity of different materials varies significantly. Experimental data shows that under the same air flow rate (1000m ³/h), the dust holding capacity of glass fiber filters can reach 250-300g, while that of ordinary folded non-woven fabric filters is only about 100g. Glass fiber, due to its fine fibers and uniform distribution, can form a denser deep filtration structure.
• Thickness and fluffiness of filter material: Using ultra thick glass fiber or chemical fiber expanded felt as the main filter layer can significantly increase the dust holding capacity. The thicker and fluffier the filter material, the greater the depth space inside, and the more particles it can accommodate.
• Fiber diameter and bulk density: The finer the fiber, the larger the specific surface area, and the higher the adsorption probability when in contact with particles of the same size. At the same time, a reasonable fiber packing density can form tortuous channels, allowing particles to be trapped in the depth direction rather than being blocked only on the surface.

• Effective filtering area: This is the most crucial variable. Within the same volume of filter frame, the larger the unfolded area of the filter paper, the higher the dust holding capacity. The non partition filter can accommodate more filter paper in a limited space through a dense pleated design, thereby achieving higher dust holding capacity than traditional partition filters. The combination filter adopts a V-shaped structure, which also increases the dust holding capacity by greatly increasing the filter material area.
• The spacing and uniformity of pleats: Whether it is a hot melt adhesive line without a partition filter or a partition plate with a partition filter, its function is to maintain a uniform spacing between pleats. The uniform spacing ensures that the airflow can fully contact every inch of the filter paper, allowing the entire depth of the filter material to participate in dust containment and avoiding premature failure caused by excessive local wind speed. Compared to rectangular channels with partitions, V-shaped channels without partitions can further improve the uniformity of dust storage.
• Layered composite filter material: The composite filter layer with gradient structure can increase the dust holding capacity. For example, a layer of fluffy fiber expanded felt is set up on the windward side as a pre filtration layer to intercept large particles, and a dense and efficient filtration layer is used on the windward side to intercept small particles. This "coarse fine" composite method can significantly improve the overall dust holding capacity.

• Filtering wind speed: Wind speed is a double-edged sword. Excessive wind speed and high inertia of particles carried by the airflow can easily penetrate deep layers of the filter material or cause "secondary dust" to scatter accumulated dust, resulting in a decrease in dust holding capacity; The wind speed is too low, although the diffusion effect is enhanced, the amount of air processed per unit time is reduced. Appropriate wind speed helps particles to deposit uniformly in the deep layers of the filter material, thereby increasing the dust holding capacity.
• Dust particle properties: The dust trapped by the filter itself will also become a new "filtering medium". Large particles and fibrous dust are prone to form loose filter cakes, resulting in slow resistance growth; Small and sticky dust can easily clog the pores of the filter material, causing a rapid increase in resistance and affecting the total dust holding capacity before reaching the final resistance.

• This is an easily overlooked but very important "human" technological factor. The dust holding capacity is not an absolute fixed value, but a test value under specific termination conditions.
• The definition of final resistance: Industry standards usually stipulate that when the filter resistance reaches twice the initial resistance, the amount of dust accumulated at this time is the standard dust holding capacity. But this setting is negotiable. If the final resistance is set to 2.5 times the initial resistance, the measured dust holding capacity will naturally be larger. Therefore, comparing dust holding capacity must be based on the same final resistance conditions.
• Efficiency decay critical point: Sometimes, the termination condition of dust holding capacity also refers to when the efficiency drops below 85% of the initial efficiency. For high-efficiency filters, the efficiency usually increases with the increase of dust accumulation. However, for some coarse or medium efficiency filters, excessive dust accumulation may cause the efficiency to first increase and then decrease, resulting in secondary dust generation, which is also considered to have reached the dust holding limit.

Summary: The technical factor that determines the dust holding capacity of high-efficiency filters is a chain from materials to design, and then to operating standards:

•  The foundation lies in the material, thickness, and fiber fineness of the filter material itself (glass fiber is superior to ordinary chemical fiber).
• The key lies in whether the structural design can maximize and evenly utilize the filter paper area (without partitions, V-shaped structure, uniform spacing).
• The impact lies in whether the operating wind speed and dust particle properties are conducive to deep dust accumulation.
• The ruler is based on the final resistance setting value as the evaluation criterion.