How Cartridge Dust Collector Filters Can Maintain Indoor Air Quality

Sep 16, 2023

Stephanie Schales, project manager, Camfil Air Pollution Control (APC) | Jun 02, 2022

Manufacturing, processing, handling, and packaging powders and bulk solids can generate nuisance and hazardous dusts and reduce indoor air quality. Facility operators must effectively collect and contain these particles to protect worker health and maintain regulatory compliance.

A proven solution is to install an industrial dust collection system that uses cartridge-style filters. Cartridge filters are cylindrical in shape, so they can hold more square meters of filter media (fabric) than panel filters. This is important because generally more media means more dust can be collected.

Unlike panel filters, cylinder-shaped filters can also be cleaned with a pulse cleaning system. Here's how it works. The media traps the airborne dust as it flows through the dust collector. As the filter cartridges become loaded with dust, the collector shoots a high-velocity pulse of compressed air into the center of the cartridge. The pulse of air expels the dust from the cartridge, where it falls down into a disposal hopper. This continual pulse cleaning process extends the life of the filter cartridges for many months, but they eventually need to be replaced with new ones.

This article looks at how to select and maintain cartridge dust collector filters to ensure good indoor air quality and cost-effective operation.

Using the right media helps to ensure good indoor air quality and to significantly reduce employee exposure to airborne particles. In addition, selecting the right cartridge filter media for your application and type of dust is key to keeping a dust collector operating efficiently over its lifetime.

Factors like dust size, shape, and combustibility help to determine the right type of filter media. The only way to get an accurate assessment of dust properties is to have an independent laboratory or equipment supplier test a sample.

Base filter media usually is either a synthetic polyester or polyester silicone blend (called spunbond) or a nonwoven cellulosic blend (called cellulose). The base fabric can be treated with a coating to provide specific performance properties such as static dissipation, oil and water repellency, flame retardance or superior release of hazardous dust particles.

Filter media can be treated with various coatings to provide specific performance properties.

Powder and bulk solids applications generate dust that fills up the filter cartridges every few minutes or seconds. When filters capture dust, airflow is restricted and the collector's fan has to work harder to keep the airflow high enough to capture the dust particles. This resistance to airflow is referred to as increased pressure drop. As your system operates, the pressure drop of the air filter is constantly increasing due to ongoing dust loading.

Dust collectors have internal cleaning systems—known as pulse cleaning or jet pulse cleaning—that eject bursts of compressed air into the center of the filter cartridge every few seconds. These air pulses push through the filter media at high velocity and with pressure of approximately 90–100 psi, which blows most of the dust out of the cartridge, so it falls down into the hopper.

In terms of filter maintenance, if the compressed air psi is too low, the filters might not be thoroughly cleaned. However, if the psi is too high, you run the risk of stressing, tearing, and damaging the media or cartridge itself. In addition, oil or water in the compressed air lines can cause pressure drop and filter media failure. Therefore, monitoring the compressed air system is an important part of filter maintenance.

Pulse cleaning of a cartridge filter

While keeping filters clean reduces pressure drop, overcleaning the filters shortens cartridge life and increases energy costs due to the overuse of compressed air. Using selective cleaning controls provides an easy way to keep filters clean. You can select from continuous cleaning, on-demand cleaning, or downtime cleaning. Continuous cleaning is best for porous dusts and high dust loading applications. For most other dust types, on-demand cleaning is recommended. This enables you to set a range of differential pressures to start and stop the filter cartridge cleaning. In this way, you can use less compressed air and achieve optimal filter cleaning efficiency and filter life.

Eventually too much dust will become deeply embedded in the filters to be removed by pulse cleaning. An indication that it is time to replace a filter is reduced airflow seen at the end of the filters’ lifespan leading to a reduction in capture velocity at a process area or an increase in dust within the process area.

Pressure drop across the collector that reduces the system's ability to capture dust is another sign that you need to change out the filter. Also watch for dust escaping the filter and re-entering the facility.

Although they constantly process high volumes of dust, premium cartridge filters can last up to a year. Filter life is dependent on the quality of the filter and whether the right media is used for the job. Using premium cartridge filters reduces replacement frequency and therefore saves on maintenance downtime and disposal costs. Long-life cartridge filters can perform for up to a year between changeouts. However, operations that generate heavy dust loading can require more frequent filter replacement.

Beware of inexpensive replacement filters, which can fail in a short amount of time, defeating the purpose. One reason is that they cannot withstand the power of the pulse cleaning system. Malfunctioning filters create a mess by sending dust into the work area, which reduces air quality, causes a potential health risk for workers, contaminates products, and can even damage equipment.

Inexpensive replacement filters can fail quickly.

When shopping for filters, pay attention to the design. Cartridge filter media is pleated. The key is to use filter media with a wide pleat because this design enables the airstream to reach 100% of the media. If the pleats are too tight, the media is compressed instead of open to the airstream. The wide-pleat design improves airflow through the filter, provides more surface area for filtration, reduces pressure drop, uses less compressed air, improves filter longevity, and saves energy. A wide-pleat filter also better releases the collected dust from the filter, which makes cleaning more efficient.

Narrow-pleat versus wide-pleat filter design

Dust collectors that require operators to enter the equipment to change out filters are a risk to the safety of workers. Fortunately, many cartridge-style dust collectors are designed so that filters are readily accessible and easily slide in and out. Dust collectors with fast-open heavy-gauge doors provide entry-free access to the filter cartridges for safe, easy replacement.

Easy access and railed platform enable safe filter replacement.

To enhance worker safety, these lockout/tagout doors are fully reversible for access from either side to prevent injury caused by accidentally opening the door during a pulse cycle. OSHA-compliant railed safety platforms and ladders with fall arrest systems can prevent slips and falls when workers access the collector to change the filter. If you are handling highly toxic dust, regulations may require a bag-in/bag-out (BIBO) containment system to isolate workers from the used filters during replacement.

Bag-in/bag-out containment systems protect workers from toxic dust during filter replacement.

Managing airborne particulates is an important part of safe powder and bulk solids operations, and filtration is at the heart of collecting and containing those particulates. Selecting and maintaining the best filters for your applications help you achieve good indoor air quality and operate your dust collector as safely and efficiently as possible.

Stephanie Schales is a project manager at Camfil Air Pollution Control (APC), where she supports mining dust collection applications and the Southeast US and Latin America territories. For more information, call 800-479-6801 or 870-933-8048, email [email protected], or visit www.camfilapc.com.

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