Aramid Filter Bags

Aokai Filter Bags

Aramid Filter Bags

Aramid filter bags are made of a synthetic fiber material called aramid, also known as Nomex. It was first developed in the 1960s and made commercially available in 1967 by DuPont. For filtration applications, it is most often known as Meta Aramid. As a filtration media, it has the following characteristics:

Efficient Particle Retention – The tightly felt structure of the aramid filter media enables it to effectively capture fine particles, thereby achieving high levels of filtration efficiency.
High Temperature & Flame Resistance – Aramid filter bags possess remarkable resistance to high temperatures without significant degradation. These aramid bags can withstand continuous operating temperatures of up to 204°C (400°F). In addition, aramid filter bags are self-extinguishing and flame retardant.
Chemical Resistance – Aramid filter bags are resistant to a wide range of chemicals, including acids, alkalis, and solvents.
High Strength and Robustness – Aramid fibers have exceptional tensile strength, which makes the filter bags resistant to tearing and bursting. They can withstand the rough handling and abrasive nature of certain dust particles, resulting in enhanced durability and reliability.
Low Thermal Shrinkage – When aramid filter bags are subjected to elevated temperatures, they demonstrate excellent stability and resistance to shrinkage. They maintain their original size and shape even after prolonged exposure to extreme heat.

In addition to these filtration characteristics, aramid filter bags also offer a number of other advantages, such as:

Extended Filter Bag Service Life – Aramid filter bags are known for their exceptional durability and longevity. The high-quality construction and chemical resistance nature allow for extended service life, reducing downtime, and minimizing maintenance costs.
Enhanced Cleaning Efficiency – Aramid filter bags have a smooth and non-stick surface that facilitates effective and efficient cleaning processes. This ensures efficient dust cake release, thorough bag cleaning, and prevents filter bag clogging.
Lower Energy Consumption – Because of its enhanced cleaning efficiency, it helps to reduce the overall pressure drop across the filter media, improving the efficiency and energy consumption of the dust collection system.
Environmental Friendliness – Aramid filter bags are eco-friendly and recyclable. They can be disposed of safely without causing harm to the environment.

Scrim-supported felt is used exclusively in the production of our aramid filter bags in order to improve filtration efficiency and extend the filter bag life. Aokai aramid filter bags are widely used in asphalt, cement, and mining & metallurgy industries.

Aramid Filter Bags

Dust Collection Characteristics

Aramid filter bags are commonly used in various industrial applications for their exceptional strength, durability, and heat & chemical resistance. They are particularly suitable for high-temperature applications, such as in cement kilns, coal-fired boilers, metal smelting processes, and chemical processes.

Characteristics	Rating
Fiber Content	100% Virgin Aramid
Weight	475g/m² (14oz/yd²)
Thickness	1.91mm (0.075in)
Fabric Construction	Needlefelt
Continuous Operating Temperature	204°C (400°F)
Maximum Surge Temperature	250°C (482°F)
Abrasion Resistance	Good
Acid Resistance	Good
Alkali Resistance	Good
Moist Heat Resistant	Good
Energy Absorbsion	Good
Filtration Property	Excellent
Oxygen (15%+)	Poor

Pros

Great resistance to highly abrasive and high temperature dust applications, extended service life, reduced energy consumption.

Cons

Higher costs, poor hydrolysis resistance, and mineral oxides can cause deterioration or partial decomposition over time.

Industry & Application

Asphalt Industry, Cement Industry, Mining & Metallurgy Industry, Power Generation.

Aramid Filter Bags

Construction & Treatment

Aramid filter media can be constructed and treated with various options so that they become best suited for various operating conditions, applications and industries.

Filter Media Construction

Needle Felting

Aramid fibers are matted together through a needle felting process, which is a traditional non-woven fabrication process by punching a fiber batt into itself to hook and entangle fibers which then form a thin, relatively dense structure, either with or without a light woven support scrim. Felts offer enhanced filtration efficiency, lower pressure drop, and higher dust-carrying capacity. They are commonly used for applications where fine particle retention is crucial. To further improve filtration efficiency and filter bag life, Aokai custom designs and manufactures Dual-Density Aramid Filter Media. In a genuine dual-density filter media, two layers of media of different densities are separated by a scrim in the middle that provides dimensional stability and a densified central core which improves filtration efficiency by minimizing dust migration through the felt. The scrim structure offers a clear advantage over unsupported felts (without scrim) which are produced in a single process with a homogeneous fiber blend and filtration characteristics only.

Spunlacing (hydro-entagling)

Spunlacing is a revolutionary hydro-entangling nonwoven fabrication process that is used to entangle fibers with high-pressure water jets. The spunlacing process creates a unique balance of lower mean pore size in a mass-efficient structure, which delivers industry-leading dust collection performance. It represents a new paradigm in filtration media by delivering a product with dramatically improved filtration efficiency, an inherent ability to promote surface dust collection, lower pressure drop over time, and a reduction in pulse cleaning cycle times.

Filter Media Treatment

Adding an ePTFE membrane to an aramid filter bag allows the membrane to act as the filter cake. Dust stays on the surface of the membrane and does not get entrained into the fibers of the filter bag, which lengthens the life of your filter bag. It also reduces wear and tear, lower maintenance costs, and energy costs due to easy dust cake release during the cleaning cycle.

The filter media is coated in a bath or spray of liquid PTFE resin. This is done to protect filter bags. The treatment improves the flex life, heat and chemical resistance, and dust release from the filter bags. This increases the service life and filtration efficiency. PTFE finish is commonly used in applications with corrosive chemical compounds, sticky dust, or high moisture contents.

This aids in filtration, adds resistance to water and oils, and improves cake release.

Helps to ground the filter bag to eliminate sparks that might cause combustion explosions.

Singeing is a finishing process where the surface of the filter media is exposed to a flame or hot gas to burn off the fine and straggly fibers in order to provide a uniform and smooth surface area, which improves dusk cake release, enhanced filtration efficiency, and better air permeability.

The singeing process typically involves passing the fabric over an open flame or through a heated chamber. The heat singes off the protruding fibers without damaging the main structure of the fabric. The process parameters, such as speed and temperature, are carefully controlled to achieve the desired level of smoothness and finish.

Glazing, also known as calendering, is the high-pressure pressing of the fabric by rollers to flatten or smooth the surface. Glazing pushes the surface fibers down onto the body of the filter media to increase and uniform surface life, improve stability, reduce shrinkage, and improve dust cake release.

Aramid Filter Bags