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Incorporating Bag Filters Into Your Treatment Systems

Deciding on which bag filters to use in your treatment system depends on many factors. For one, it’s important to consider which type of filter housing is necessary for your needs: single or multiple bag housing. Next, you must decide which type of filter bag the project requires.

Bag Filter Housing

The housing of the bag filters should be considered before any purchase is made. This ensures that the bag filters are sized correctly for the water treatment system. The first point to consider is the flow rate that the water needs to be filtered at. If the project calls for a high flow, selecting a multiple bag filter will allow all of the water to be filtered by only using one housing. However, if the project is smaller, it might not require the extra filtration afforded by a multiple bag unit. In this example, a single bag unit would be more appropriate.

The next point to consider is the material of construction of the housing. Industrial water and wastewater projects typically use 304 stainless steel. In applications where oils, coolants, or caustic fluids need to be filtered, carbon steel is much more commonly used. For filtration of acids, and other corrosive materials, 316 stainless steel, or other higher grades of steel are required.

Which Bag Filter To Choose?

Along with the choice of housing for the bag filtration system, selecting the correct filter for the job is essential. Anyone installing a filter system needs to consider the type of liquid to be filtered and the material that needs to be removed.

Starting with what is being filtered, an activated carbon impregnated bag filter is an excellent choice for the removal of heavy metals, VOCs, BOD, and other organic compounds. It is able to adsorb dissolved material from water. If oil needs to be removed from water, an Oil Absorption Bag Filter is the best choice. The multi-layer design increases the chances of oil droplets colliding with and absorbing onto the polypropylene material as the water passes through the bag. Nylon Mesh bags are frequently used in applications where more porous bags are needed (greater than 100 micron).

The two most common materials used in bags are polypropylene, and polyester. To decide which material to select, first consider the liquid being filtered. Polypropylene offers excellent chemical resistance, and is often selected when acids, bases, or water needs to be filtered. Unfortunately, polypropylene swells when it comes into contact with oil, which can prematurely clog the pores of a bag. For this reason, polyester is used when filtering oils, coolants, and solvents. Polyester can also be used for water or weak acids.

To create the perfect filtration system for your project, consider the above suggestions before determining which bag filter you need for your treatment system.