Regardless of its composition or structural design, the primary purpose of any filtration device is to remove any unwanted solid materials that may be present in a liquid. The bag filter is no exception, although it can also be a means to remove particulate matter from the air. A classic example of the latter application is the cloth bags that store the dust in a conventional vacuum cleaner. The fabric retains the particulate matter while allowing the continuous stream of air to pass through and escape through the machine’s exhaust port.
Across the entire spectrum of industry, dozens of processes rely on some form of filtration technology. Most often, these processes involve solid/liquid separations, and a bag filter will frequently be the tool of choice. Let us take a look at some common examples.
Water and Wastewater Treatment Plants
To render water safe to drink and palatable, it must undergo a series of processes to ensure it is as free as possible of particulate matter, both visible and microscopic. The goal remains the same whether the untreated source is wastewater produced by domestic or industrial consumers or water drawn from rivers and lakes. After straining to remove larger solids, such as leaves, and sand filtration for finer particles, a polyester bag filter impregnated with activated charcoal can provide a final polish and offer an alternative to more costly reverse osmosis.
Breweries and Distilleries
Just as with water purification, there are numerous steps in the process of producing alcoholic beverages, such as beer, wine, and spirits. During many of these steps, it is necessary to remove various undissolved solids present in the liquid that forms the basis for each of these products. For example, it is essential to remove traces of grain while leaving behind the sugars formed during fermentation. Typically, a bag filter will provide the means to achieve this.
The presence of protein can tend to retard the fermentation, while modern tastes make it necessary to remove any residual sediment before bottling. In each case, the same type of device offers producers a practical solution, although its pore size and type of fabric will vary according to the size and concentration of particles to be filtered.
Whatever the application, these units need to be mounted in a special housing that typically accommodates multiple units during use. A bag filter may be woven or assembled using needle-punched fibres and fashioned from materials, such as felts, nylon, polyester, and polypropylene, to name a few. Flow Clear Filtration offers South African industries a comprehensive range of high-quality filtration equipment for an equally wide range of applications.