Q&A: Dust collection system basics

What types of applications is each collector type best suited for and why? 

Cartridge collectors are meant to handle finer dust particles. The filter media that goes into a cartridge collector can be made to separate a much smaller particle size from the airstream, in the micron and submicron range. For example, a cartridge collector with cellulose filter media is suited for dry and fine dust from thermally generated processes, such as welding, thermal spraying or plasma or laser cutting. Cartridge dust collectors are also well suited for dry bulk material handling processes such as pharmaceutical applications or the conveying of various dry bulk materials. 

Because baghouses use felt filter media, they are generally more suited for larger particle sizes and industrial applications with higher air volumes and grain loadings. They can also handle higher temperatures, chemical applications, moisture and other nonstandard airstream characteristics. 

What are the main factors to consider when selecting a dust collector? 

There are many, but the main thing to target is the type of dust you are trying to collect. Again, submicron particle sizes will lean toward a cartridge style collector, while heavy-duty applications or nonstandard dusts will lean toward a baghouse. 

Within the cartridge or baghouse technologies, you want to look at where the dust collector will be located. Whether the collector will be located outside or inside the building may impact footprint requirements or height restrictions. Sometimes process requirements can be a factor. For example, if the process airstream must be conditioned, the collector may need to be inside the building. 

Another factor to focus on is how long you will run the process. If you have a critical process that needs to run 24/7, you will want to find equipment that is constructed and sized for that level of operation. If your application will only run for a couple hours each day, you may be able to size the system more aggressively or go with a different technology. 

What are the most common types of dust collector filter media, and how can processors determine which type is most suitable for their system? 

Cellulose and polyester media are the primary types on the market. Our standard cartridge media is called Ultraweb, which is a cellulose media with a fine fiber. Our standard baghouse media is called Duralife, which is a polyester media. What you need to look out for are the nonstandard airstream characteristics I mentioned previously. If you have high temperatures, moisture or chemicals in your airstream, you will need to look for a specialty media that is more suitable for those conditions. 

Cellulose is made from the same thing as paper. If you get a piece of paper wet, it will start to wrinkle and weaken; the same is true for cellulose filter media. If you have moisture in your process, you will want to use a felt or polyester spun-bond type of media. 

You also need to consider the dust’s physical properties. If you have a dust that is stringy or fibrous, such as shredded paper or cotton dust that may clump together, you may want a media with a wider pleat spacing or a different configuration. It is not only the media type but the filter configuration that can be important. 

How can processors compare different dust collectors on the market? 

I would recommend really looking at the system’s total cost of ownership. A lot of end users are just focused on the initial cost of the equipment. Dust collectors are definitely not cheap, especially when you start adding in all of the system components, but you should look at the operating costs as well as the initial costs. How much compressed air will the system use? How often will you need to perform maintenance? How long will the filters last? How long will the equipment itself last? All of these factors will impact the total cost of ownership and help you understand what an equipment manufacturer can do for you. 

Dust collection equipment often seems the same across different manufacturers, so look at the manufacturer’s support for the equipment, both presale and post-sale. Does the manufacturer have service capability? Can they supply filters? These things can all factor into the total cost over the life of the equipment. 

What should processors consider when determining where to locate a dust collector in their plant? 

The first consideration is physical space. The amount of airflow you need and the volume of the material you are trying to move will dictate the size of the equipment. Do you have space to put the equipment inside your facility, or do you need to put it outside? Some processes will require that the equipment is located inside to keep the dust in a state that is easy to convey. 

For example, if you collect sugar dust and convey it to a collector located outside in Louisiana, where it can be very hot, you are going to have melted syrup inside that dust collector, which will be a major material handling challenge. Some dust types, like sugar, need to be in a controlled environment where the air is conditioned, and the airstream is the same temperature throughout the collection system to make moving the material in and out of the collector a lot easier. For such materials, the process will dictate the collector location. 

Regulatory or compliance issues may also come up. If you are handling combustible dust, locating the collector outside allows you to use different explosion mitigation strategies than if you locate the collector inside the building. 

What are the most common causes of dust collector failure or inefficiency? 

I would say lack of maintenance. Dust collectors tend to be forgotten in many cases. Companies want and need the system to work, but it is only when the system stops working that it gets attention. Keeping up with periodic maintenance is critical, such as checking the differential pressure across the filters to see if there is a leak or if the filters are nearing the end of their life and you need to order new ones. 

You should also regularly check the compressed air to make sure it is clean and dry. Most traditional dust collectors have some sort of pulse-jet cleaning system that uses compressed air to clean the filters. The compressed air must be clean and dry to effectively clean the filter media. It is also a good idea to keep spare parts or repair kits on hand to fix leaks or failures. And check discharge containers to make sure there is no leakage and that they are sealed properly.