What are the factors that affect the effective filtration area of the folding filter element?

In the past, the size of the cartridge was derived from the size of the coil filter, which was approximately 10 inches by 2.5 inches. Increasing the size of these cartridges will increase their effective filtration area (folds per unit number). Most manufacturers offer cartridges with a diameter of 2.75 inches (70mm). Diameters and joint types are often standardized or similar, which gives filter users more choice. Due to the use of universal connectors, no additional capital investment is required in different filter housings.

Cartridge filter

In addition to the cylinder diameter, two other factors contribute to the increase in effective filtration area. The first factor is the diameter of the inner shaft of the cartridge. Each pleated layer contains one or more membrane layers sandwiched between two protective layers, the presence of which is necessary to avoid damage to the membrane during the pleating process and to effectively keep the pleated layer separate and act as a drainage layer in the formed filter cartridge. Due to the existence of the "sandwich" structure, each fold naturally has a certain thickness. The smaller the diameter of the inner axis, the fewer folds can be arranged around it. Therefore, an increase in the diameter of the inner axis will lead to an increase in the circumference and an increase in the number of folds surrounding the inner axis. This determines the number of folds possible in the pleated package that makes up the membrane cartridge, thereby increasing the effective filtration area.

Folding filter element

Another consideration is the preference for larger diameter internal shafts. Especially for the use of longer cartridges with elevated pressure differentiations, the flow of fluid through the microporous membrane can be so large that the "narrower" diameter of the longer inner axis limits the flow of fluid through. Thus, for a pleated cylinder structure intended for high water flow, the outer diameter of the cylinder may be up to 12 inches to accommodate the maximum number of high pleated layers, or more pleated layers may be arranged around an inner axis with a diameter of 10 inches. In addition to the height of the fold, this factor extends the service life of the filter by increasing its effective filtration area and increases the flow rate of the filter.