Collecting Pharmaceutical Dust: Improving Safety and Efficiency Through Advancements in Pharmaceutical Dust Collection Technology

Dust in the pharmaceutical industry is ever-present. Nuisance dust is generated from most process steps — from the handling of bulk materials and ingredients to milling, granulating, tableting, encapsulating, coating, and even product packaging. Due to the fine nature of pharmaceutical dust, maintaining acceptable housekeeping standards and reducing process-related hazards can be a full-time job.

Pharmaceutical dust can pose several challenges in the workplace, such as conforming to current good manufacturing practices (cGMP), avoiding cross-contamination of parallel processes, managing employee exposure to materials, and reducing combustible dust-related hazards.

Not properly handling or containing process dust can lead to steep OSHA fines, production downtime, worker dissatisfaction, and reputational damage. With so much at risk, it’s important to understand pharmaceutical dust filtration options and the available technology to help improve the safety and efficiency of your plant.

Evolution of Dust Collector Housing Design

Dust collection technology has significantly evolved over the past several decades to allow for smaller and smarter equipment. In many of today’s powder processing facilities, we no longer see traditional baghouse dust collectors standing tall and outside as part of the building silhouette. Dust collection technology changed in the mid-1970s with the introduction of the cartridge filter. This revolutionary design placed more filter media in a smaller area and allowed process owners to re-evaluate their dust collection strategy and equipment location.

For pharmaceutical manufacturers whose processes generated fine or light dust, the cartridge collector allowed dust collection equipment to be placed inside plants allowing maintenance personnel to service dust collection equipment more easily. This usually meant fewer trips to the roof or climbing into equipment. This progress reduced downtime for maintenance and improved productivity.

Early cartridge dust collector designs showed advancements over previous baghouse technology, but still left room for improvement. Like a baghouse, vertically oriented cartridge filters and low-entry inlets resulted in dust re-entrainment issues and material handling challenges. By the early 1980s, however, new designs incorporated downward airflow patterns that leveraged gravity to remove more dust from the airstream.

Downward airflow designs, supported by EPA research and endorsed by the American Conference of Governmental Industrial Hygienists (ACGIH), were identified as the most efficient cartridge dust collector housing designs. Still today, downward flow technology is able to remove efficiency barriers with lower pressure drop and help reduce re-entrainment issues, providing an overall design that allows particulate to fall easily into the hopper.

Analyzing Airflow Patterns

To better understand how housing design and airflow direction impact operational performance, compare the two different design methodologies: upward airflow (or cross-flow) and downward airflow.

With either dust collection strategy, the goal is to filter the collected pharmaceutical dust and return clean air to a process or facility. High velocities within a dust collector housing will impact the system's performance and prohibit the collected material from discharging out of the dust collector. This leads to dust re-entrainment on the filter elements, which results in higher pressure drop, higher energy consumption, and higher overall operating costs.

As shown in Figure 1, in an upward airflow unit, the “cross-flow” effect results in uneven air velocity distribution and significant areas of higher velocities, prompting greater potential for filter abrasion. Staggered inlet baffles create turbulence in the hopper and can cause dust re-entrainment and difficulty pulse cleaning, resulting in higher pressure drop and shorter filter life.

Dust collectors that utilize a downward airflow design, as shown in Figure 2, are able to better leverage gravity to direct incoming air and dust into a dropout zone located within the dust collector. This design reduces turbulence and moderates dust loading on filter elements, resulting in lower energy consumption, more efficient pulse cleaning, and longer filter life for your operation.

Dust Containment

Many pharmaceutical byproducts contain hazardous or toxic dust. This material may contain an Active Pharmaceutical Ingredient (API) such as a narcotic, hormone, steroid, or other compound that could be harmful to employees or the environment if not controlled correctly.

Unlike standard processes that generate passive dust, noxious dusts need to be handled in a manner that limits exposure to employees and the environment. Containment strategies can become unique challenges due to filtration equipment taking on a dual role as both collector and containment vessel for the collected dust.

Today’s dust collectors are often confined to run continuously. Equipment options allow dust collector controls to monitor pressures, regulate airflow, automatically pulse-clean filters, and even discharge dust from the hopper without stopping the process. “Connected” dust collectors can even prompt timely maintenance and service, improving production uptime and reducing operating costs.

Dealing With Dust

Even with high levels of automation, there are still manual tasks required to keep collectors operating efficiently. Routine maintenance, such as changing filter elements or removing discharged material, presents opportunities for employees to be exposed to hazardous material. To help manage exposure during maintenance periods or support general housekeeping strategies, many operations will outfit their dust collection equipment with Bag-In/Bag-Out (BIBO) modifications.

The term “BIBO” refers to the use of special bags and a handling process that allows an operator to change filters without direct exposure to the dust in the collector. The operator removes the expired filter by affixing a bag to the filter access area and closes and seals the bag as the filter is withdrawn. As there are different variations of BIBO offered across the industry, here are a few things to consider when determining BIBO's effectiveness:

• All bags are not rated equally. Bags should come from containment experts and be made of material that is suitable for the dust that is being collected and contained.
• Circular-shaped BIBO collars tend to be more effective than rectangular collars because they provide an even seal around the surface. Rectangular collars are more prone to gaps or air leakage on flat surfaces.
• When considering BIBO equipment, look for equipment specifically designed for BIBO procedures.

In addition to BIBO equipment, effective personal protective equipment (PPE) should be used to perform any routine maintenance process.

Combustible Dust Management

Many pharmaceutical dusts are also considered to be a combustible dust hazard. Together, OSHA and the National Fire Protection Association (NFPA) have created emphasis programs and written standards around managing and mitigating combustible dust hazards.

As part of a Dust Hazard Analysis (DHA), process owners are required to understand the hazards of the material(s) in their facility and review any process-associated risks. There are many different mitigation strategies available to help prevent and protect equipment from combustible dust events. When assessing the hazards in a facility, it’s important to work with experts who can help recommend controls that are appropriate for the process and hazard.

For a fire to occur, three key elements need to be present: oxygen, heat, and fuel. Remove one of these elements, and the risk is eliminated. For an explosion, five elements must combine — those necessary for a fire plus two others: dispersion (dust suspended in factory air) and confinement (dust concentrated in a small space). To mitigate an explosion risk, strive to remove one or more of these five elements.

Better Work Experience, Better Products

Advancements in pharmaceutical dust collection technology make it possible to not only reduce safety risks but also provide a cleaner workspace for employees. When upgrading or purchasing new equipment, it’s important to work with a provider who understands potential workplace hazards and can recommend equipment to meet performance expectations.

Author Details

Chrissy Klocker, Technical Services Manager - Donaldson

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