EN 779 Synthetic Fiber Medium Pocket Filter

Pockets filters are widely used in central air conditioning ventilation systems, pharmaceutical, hospital, electronics, food and other industrial , and can also serve as the medium filter for high-efficiency air filters.

This is the key component that determines filtration efficiency, primarily made from synthetic chemical fibers.

Main Types:

Synthetic Fiber: This is the most commonly used and mainstream material. It offers good strength, stable performance, and high cost-effectiveness.

Polypropylene Fiber: This material possesses good chemical corrosion resistance, remains stable especially in humid environments, and is not prone to mold.

Material Form and Manufacturing Process:

Non-woven Fabric: The vast majority of synthetic fiber bag filters utilize the non-woven fabric process. Fibers are randomly interlocked through methods like needle punching, melt blowing, or spun bonding, forming a three-dimensional web of varying depth.

Structural Characteristics: This disordered structure creates countless curved, intricate micron-sized channels that capture particulate matter through the following mechanisms:

1. Interception Effect: Particles are directly trapped on the fibers.

2. Inertial impact: Larger particles deviate from the air streamlines due to inertia and collide with the fibers.

3. Diffusion Effect: Very small particles randomly collide with fibers due to Brownian motion.

4. Electrostatic Effect: Some synthetic filter media carry an electrostatic charge, which enhances the adsorption capacity for fine particles.

Support and Structural Frame Materials

To enable the soft filter media to function stably, the following structural materials are required:

Bag Support Frame: Inside each filter bag, there is typically a V-shaped or U-shaped support frame made of galvanized steel wire or plastic.

Function: Prevents the filter from collapsing under airflow during operation, ensuring each filter bag remains fully expanded. This guarantees maximum effective filtration area and lower system resistance.

Frame Materials:

Galvanized Steel Sheet: The most common choice, offering good strength and low cost, meeting the requirements for most air handling units.

Aluminum Profile: Lighter in weight with good corrosion resistance, often used in weight-sensitive applications or special environments.

The efficiency of pockets filters ranges from 45% to 95%, and they can be selected based on specific requirements. The rational selection of filter efficiency and face velocity contributes to comprehensive economic benefits.

For filters made of the same material, higher efficiency typically results in greater resistance and higher cost, while lower efficiency leads to reduced resistance and cost. Altering the air velocity will also affect resistance, efficiency, and the number of filters required, so appropriate selection should be made according to specific conditions.

As dust accumulates on the filter media, the resistance increases. When the resistance reaches an unreasonable level, the filter must be discarded. Sometimes, excessive resistance can cause previously captured dust to become dislodged and re-enter the airflow; when this risk arises, the filter should also be replaced. The resistance of a filter increases with higher airflow rates. By increasing the surface area of the filter media, the relative velocity of air passing through the filter can be reduced, thereby decreasing the resistance.

Remarks: (1) Initial resistance tolerance of± 10%   (2) Support customer size