Airborne dust is produced by various sources across multiple industries, including construction, mining, metalworking, foundry work, food and beverage processing, pharmaceutical manufacturing, and more. This dust can range in size from large particles visible to the naked eye to tiny particles that require a microscope to be seen. Regulations require manufacturers to meet environmental standards by reducing emissions, typically achieved through the use of environmental equipment like baghouses or dust collectors.

Operating environmental equipment effectively involves understanding its features, components, and the scientific principles that govern its function. A fundamental grasp of industrial air filtration—specifically how it removes dust particles from demanding manufacturing processes—is essential to keeping your dust collector or baghouse operational at a lower cost.

Understanding Industrial Air Filtration in Baghouses

Baghouses employ industrial air filtration to physically capture dust particles using a filter media, usually made of fabric. It is important to understand that this is a physical process, not a chemical one, meaning the dust particles are not destroyed but collected on the filter media.

When dirty, dusty air enters the baghouse, it is directed through fabric filters known as baghouse filter bags. Larger dust particles are often removed by contact with an internal target plate. As the turbulent air rises, finer dust particles are drawn into the filter media, where they are captured. The cleaned air then passes through the filter media into a clean air plenum before being exhausted into the atmosphere or returned to the process. The collected dust is periodically cleaned off the filter bags by blowing air through them, causing the dust to fall into a hopper for disposal.

Principles of Industrial Air Filtration

Four key scientific principles explain how industrial air filtration works with baghouse filter bags, helping buyers understand the effectiveness of different fabrics in air cleaning:
 

Principle #1: Direct Interception

Particles larger than the pores in the filter medium are removed through direct interception. These particles are physically trapped by the fibers and cannot pass through the filter.
 

Principle #2: Inertial Impact

When particles collide with the fibers of the filter media at high speeds, they are deflected or slowed down by the impact and eventually trapped by the fibers.

Principle #3: Diffusional Interception

Particles on a collision course with flow stream molecules experience frequent collisions, causing them to move randomly around the flow lines. As they diffuse through the filter media, they contact more fibers and become trapped.

Principle #4: Sieving

Particles that are too large to pass through the pores of the filter media are physically trapped and cannot pass through the filter.

Choosing the Right Air Filter Media: Woven or Nonwoven

Selecting the appropriate filter media is crucial for successful air filtration and reduced emissions. Manufacturers can choose between woven or nonwoven filter media based on their baghouse OEM specifications and manufacturing processes. Nonwoven media often perform better due to their web-like structure, which provides various pore sizes for dust particles to pass through and attach to the fibers, while allowing cleaned air to pass through. Nonwovens also offer enhanced properties like chemical and high-temperature resistance.

When purchasing baghouse filter bags, it is essential to consider the total cost of ownership, beyond just the initial purchase price. Manufacturers must factor in installation and maintenance costs. The chosen air filter medium impacts utility consumption (electricity or compressed air), emissions, and potential downtime. Additional considerations include operating conditions (temperature, humidity, corrosiveness), the air-to-cloth ratio, and the dust’s physical characteristics (stickiness, abrasiveness, etc.), all of which influence the best-suited filter media for your application.