What Is a Pleated Filter?
Pleated filters are filters that are formed in a pleated shape to increase the surface area per volume and improve filtration performance. Filters have different characteristics depending on their structure, and it is necessary to select the structure that best suits the purpose and application.
Pleated filters are preferred for applications requiring low pressure drop and reliable capture of particles above a certain size. While surface filtration types like pleated filters are generally suitable for microfiltration due to their small particle size and high removal rate, the increased surface area relative to the flow path results in a large pressure drop. Pleating is used to enhance the surface area per volume, helping to mitigate this issue.
Uses of Pleated Filters
Pleated filters are suitable for use in microfiltration and a variety of other filtration applications, making them versatile in a wide range of industries. Examples include:
- Filtration of various compounds and chemicals, such as petrochemicals, paints, and inks
- Removal of impurities in water, including primary filtration in pure water production and filtration of cooling water, cleaning water, etc.
- Removal of metal fragments in water used for cutting and polishing machinery
- Filtration in water supply and drainage facilities, swimming pools, hot tubs, etc.
- Filtration of natural water sources like well water and ground water
Microfiltration, ideal for smaller-scale filtration equipment, may clog when capturing larger particles.
Principles of Pleated Filters
Pleated filters optimize surface area per volume through their pleated design, thereby enhancing filtration performance. It’s important to choose a filter based on structural characteristics and specific application needs.
Cartridge filters are categorized into three main types: depth (Debs) filter type, surface filter type, and adsorption/exchange filter type. Pleated filters fall under the surface filtration category and are commonly used in industrial cartridge filters.
However, an increased surface area relative to the flow path can cause significant pressure loss. Pleating is employed to counterbalance this pressure loss.
Thus, they are especially useful where low pressure drop is desired and for capturing particles larger than a specific size.
Materials like polypropylene are commonly used, but options like PE ether sulfone, PTFE, PVDF, nylon, and glass fiber with excellent chemical resistance, diatomaceous earth for beverages, and stainless steel for corrosive fluids are also available. Some filters combine materials of varying fiber diameters for gradient filtration accuracy.