Dust has been one of the biggest air pollutants over the years. Dust extraction and collection systems are thus designed to eliminate dust particles at home and commercial settings. However, the dust collection system’s performance will depend on several factors such as location and number of dust collection points, duct diameter, and dust particle size, to mention just a few. A simple miscalculation when designing such a system can lead to costly performance issues.
Understanding how dust extraction systems work is thus important before you commit to buy one. The following are some of the questions to guide you:
Does particle size distribution matter?
Dust particles usually appear in different sizes and shapes. Some of the factors that determine the size include the composition of the parent material and the processing machine’s nature that creates these particles. For instance, you will find some differences in the dust from the sawdust from a chainsaw from the dust you get from gravel in a construction site. The variance in the particle size is also known as the particle distribution. The dust extraction system company will thus be interested in the particles’ size for several reasons. Some of these particles can be inhaled and thus affects industrial hygiene standards. Dust collectors are designed to be permeable to air. However, such collectors may fail to trap dust if the particles are extra-small. Experts in this field must also check the dust particles’ combustibility and their ability to be disbursed during an explosion.
Fan wheel-style; does it affect performance?
One of the most important components in typical dust collection systems is the exhaust fan. It is this component that provides the motive behind the entire system. The system is thus bound to fail if the exhaust fan is not performing as expected. The fan must thus generate enough pressure and volume that will pick dust particles. There are three different types of wheels:
Air handling wheel
Such wheel cleans extremely light dust loading or clean airstreams. Such wheels should never be used on the dirty side but the clean side.
It works best when the fan is on the dirty side of the dust collector. One of the best places where such wheels are used is in material handling. An open-type wheel applies best when the dust is fibrous or when there is a high dust loading. The design is meant to prevent/protect the dust from wrapping around the wheels.
Such wheels are not common on dust collection systems. They typically move a lot of air, but the force behind them is negligible. The material used to make such fans is an important consideration as abrasive specks of dust can erode those fans made from soft metals.
What is a damper?
A damper is a tool in a dust collection system that controls airflow to a specific branch of the ductwork. The dampers usually open and close, thereby allowing air to pass through. Air always uses a path with the least resistance. Typical dust extraction and collection system will have a damper near each pickup point or hood that allows the system to be balanced. It is this flexibility that will allow airflow to be varied across collection points. An unbalanced system could cause uneven pulling of air within an area. There are spaces or soft connects between flanges that control the airflow at pickup points. However, the approach is not that effective as it keeps the airflow constant in that specific area, even when it is not necessary. Dampers are more effective than soft connects as they close off branches that are not being utilized.
What is load in dust extraction?
Most dust collectors such as cartridge collectors and baghouses use filters and bags to separate dust from the air. Such collectors use fabric filters, which means that there is likely to be a negative impact on the performance when there is excessive dust loading. If a baghouse has a higher than 5-7 grains/cu ft concentration, then expect that there will be maintenance and operational issues. On the other hand, the load should be below 2 grains/cu ft if you are dealing with cartridge collectors. The airflow that goes through the collector is greatly reduced when the filters are overloaded, which leads to overall system inefficiency. The collection process thus becomes expensive as the system does not collect dust as it is expected. You must also replace the filters often, which means that the system will be offline on many occasions. There are also high chances of air getting into the environment.
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