Dust collectors are important tools in any industrial manufacturing operation. They provide a cleaner environment for employees, eliminate air quality concerns, and meet environmental compliance directives. Downward flow cartridge dust collectors are commonly used in processes to remove pollutants in grinding, sanding, thermal spraying and making graphite, ink dyes, silica talc and toner. Choosing an optimally designed downward flow dust collector is key to controlling the air quality in your plant. To ensure your dust collector performs to its full potential, using the most advanced, and efficient filtration technology is critical. This winning combination will maximize overall system performance and efficiency resulting in major energy savings and reduced operating costs. Let's take a look at factors to consider when selecting a downward flow dust collector and the best type of filtration to go along with it.
There are two important factors to consider when choosing a downward flow dust collector:
- Quality of the filter media
- Performance of the cleaning mechanism
Quality of the filter media
When it comes to dust collector filtration technology, there are basically two types of cartridge dust collection filters available:
- Traditional commodity filters
- Advanced nanofiber technology filters
Substrate material and surface coating
Traditional commodity filters are straight cellulose with one homogenous layer of cellulose fiber. Blended cellulose filters typically consist of 80 percent cellulose and 20 percent synthetic fiber. Commodity filters sometimes come with a melt-blown surface layer added to improve efficiency at capturing submicron particles.
The surface of any filter cartridge media contains holes or open space. Media with smaller holes will be more efficient at capturing fine particles. Using a material with the smallest fibers possible offers the highest efficiency rating.
The most technologically advanced type of filters available are nanofiber filters. This type of filter media uses fibers as small as 1/1,000 of a micron. To put this in perspective, there are over 25,4000 microns in an inch! That means that a nanofiber filter can capture submicron-sized particles.
Efficiency and MERV rating
To assess a filter's efficiency, the most accurate measurement available is the MERV (Minimum Efficiency Reporting Value) system. The higher the MERV rating, the better the filter's efficiency at removing submicron dust particles from the air and reducing emissions. MERV ratings are based on a scale of 1 to 20, and classified into three particle size ranges:
- Range 1 – 0.30 to 1.0 micron
- Range 2 – 1.0 to 3.0 microns
- Range 3 – 3.0 to 10.0 microns
Standard commodity filters typically achieve a MERV rating of 10, meaning that they are only able to capture particles 1.0 micron and larger in size. In fact, they are not even efficient enough to be rated in range 1 because they cannot capture dust that is in the .30 to 1.0 micron size range. In other words, submicron dust passes right through commodity filters and back into the workspace and your employees’ breathing zones!
Nanofiber filters, on the other hand, achieve a MERV 15 — the highest of any standard cartridge filter. This means that nanofiber filters are 85 - 95% efficient at capturing particles 0.30 to 1.0 micron in range 1 and more than 90% efficient at capturing particles 1.0 micron-sized and larger in ranges 2 and 3.
Low pressure drop
Nanofiber filters offer the highest possible efficiency and effectively prevent particulate from building up within the filter’s substrate and restricting airflow. Because of this, pressure doesn't build up as fast as it will in a lower efficiency commodity filter. A low pressure drop means the dust collection system needs less energy to run and can use a less expensive blower.
An unavoidable by-product of the filter cleaning process is that a small percentage of the collected dust is released back into the atmosphere. Because nanofiber filters require less frequent pulse cleaning, total outlet emissions are reduced.
Commodity filters typically emit up to 35 times more dust back into the atmosphere than nanofiber filters.
Performance of the cleaning mechanism
To dislodge dust from the filters into a collection bin, most downward flow dust collectors use pulse-jet cleaning technology — a process where the system’s cartridges are cleaned by a blast of compressed air, causing dust to pulse off into a drawer or hopper for disposal.
Pulse-jet cleaning systems used in downward flow cartridge dust collectors are similar, but they differ in several ways that can significantly affect cleaning efficiency, ease of use and filter life. It’s important to carefully consider the performance of the cleaning system when evaluating a downward flow cartridge dust collector. Here’s what to know:Nozzle and venturi design
These key components determine the cleaning achieved with each blast of compressed air. Systems with a poorly designed nozzle and venturi cannot pulse the air with enough velocity.
Choosing a system that is optimized for the spacing of the air nozzle, as well as precisely calculated geometry of the venturi ensures that the air is pulsed with enough power to completely clean the entire length of the filter.
Some systems use an internal yoke support which can actually act as an obstruction that blocks the pulse cleaning jet — creating turbulence and less cleaning power. A system with filters that rest on rails is a better choice because there are no internal blocks at any point along the cartridge filter – resulting in up to 25 percent more cleaning power.
Selecting a downward flow dust collector that combines an optimized cleaning system and uses the advanced surface-loading capabilities of a nanofiber filter directly results in less pulse cleaning cycles (less compressed air use) and longer filter life. A commodity filter may pulse as much as 17 times more than an advanced nanofiber filter, resulting in considerable compressed air costs. Likewise, using nanofiber technology can double the filter life and cut replacement filter costs by 50 percent!
The design of the dust collector’s cabinet directly affects airflow and cleaning efficiency. Choosing a design that evenly distributes air throughout the cabinet is optimal.
The cabinet should be coated entirely with an electro-statically applied, powder-coated finish to prevent fading and chalking. And, it should be manufactured with 10 gauge steel and meet Seismic Zone 4 and 100 mph wind load ratings to ensure performance in harsh outdoor conditions.
Some systems use angled filters which can cause dust to accumulate against the inside of the door and on the top of the filter. When the door is opened, dust can fall on the maintenance worker. Ensure the design features a simple, replacement process, such as a push to seal closure that eliminates the need to turn knobs and hook latches.
Selecting a system that offers a modular design is ideal when you need to increase capacity.
It’s always a good idea to choose a system from a well-known manufacturer that offers premier customer support to ensure your equipment meets all environmental requirements and operates effectively well into the future.
One such system that meets all of the above requirements is Parker’s DustHog SFC Downward flow dust collector. The SFC effectively removes dust, fumes and smoke from industrial manufacturing processes and applications. It comes standard with the industry-leading ProTura® Nanofiber cartridge filters for more efficient and effective collection of dust emissions and capture of submicron airborne pollutant particles. The patented pulse cleaning technology provides optimized cleaning power to most effectively pulse off dust from the filter resulting in increased pulse cleaning energy, lower pressure drop, longer cartridge filter life and energy savings.
Watch this video to learn more about the Parker DustHog SFC Cartridge Dust Collector System:
A cartridge dust collector is an important investment that impacts the performance of the equipment in your operation and the health of your employees. To realize the greatest return on your investment and provide the safest work environment possible, your best option is to choose a surface-loading nanofiber filter and dust collection system that also offers an optimized cleaning system to gain the maximum benefits of the filter’s capabilities.
This article was contributed by the Filtration Team.