How does a bag filter work?

As a highly efficient solid-liquid separation device, the working principle of the Bag Filter is mainly based on the interception of solid particles or impurities in the liquid by the filter medium. Specifically, the working principle of the bag filter can be summarized as the following steps.

1. Preparation for filtration.

The liquid to be filtered is introduced into the inlet of the bag filter through a pipe. Ensure that the liquid is evenly distributed before entering the filter for more effective filtration.

2. Filtration process.

The liquid flows into the filter bag from the inlet of the filter under pressure. The filter bag is made of porous and loose filter materials such as polypropylene, nylon, polyester, etc., and its pore size determines the filtration accuracy. When the liquid passes through the filter bag, impurity particles larger than the pore size of the filter bag are trapped on the surface and inside of the filter bag to form a filter cake layer. At the same time, smaller particles may also be captured due to Brownian motion, electrostatic adsorption, etc. Clean liquid is collected along the designed path through the pores of the filter bag, and finally flows out from the outlet at the bottom or side of the filter.

3. Pressure difference monitoring and control.

As the filtering process continues, the impurities accumulated on the surface and inside of the filter bag gradually increase, resulting in an increase in the filtering resistance and an increase in the pressure difference between the inlet and outlet. When the pressure difference reaches the set threshold, it is usually a signal that the filter bag needs to be replaced or cleaned.

4. Replace or clean the filter bag.

When the filter bag reaches saturation or the pressure difference is too high, it needs to be replaced or cleaned.

In short, the working principle of the bag filter is to intercept and separate the solid particles or impurities in the liquid through the filter bag, so as to achieve the purpose of purifying the liquid. It has the advantages of high filtering accuracy, large processing capacity, small volume, and large dirt holding capacity.

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Nina

Email: nina@filtrationchina.com

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