Cartridge Filters And Their Types – Explained

Types of Cartridge Filters

Cartridge Filters are cylindrical shaped filter elements produced from either a polymer or stainless steel. There is an array of polymers which can be moulded into cartridge filters; and based on their characteristics and production technology the applications of the filter are worked out. During production of cartridge filters the process parameters are adjusted to achieve a specific porosity. The porosity is measured in microns (micrometers) wherein 1 micron = 0.001 mm. The liquid is forced to travel through the filter medium of the cartridge filter to make the filtration happen. In doing so the suspended solids which are larger than the pores are trapped within the medium of the filter.

Types of Cartridge Filters

There are numerous types of cartridge filters available in the industry. But broadly they can be divided into two categories: depth filter and surface filter. Depth filter, as the name suggests, has thick filter media. The fluid when travels through this kind of media, the suspended solids get trapped within the matrix of the filter media. Surface filters, as opposed to the depth filters, have thin layer of filter medium; the suspended solids get retained right on the surface of the medium. Based on the construction, the cartridge filters are classified as:

Wound Cartridge Filters

Also known as string wound filters, these depth-type filter elements are produced by winding the polymeric yarns (mostly of polypropylene) around a core. It is the quality of the yarn and efficiency of the process that define the performance of the filter element. Wound filters have been around for a while but lately the enhancements in production technology have made them more efficient.

Melt Blown Cartridge Filters

Melt blown cartridge filters are depth-type filters. They are produced from granules of polymers; the most widely used are the ones produced from polypropylene. As the name suggests, the granules are melted, and with the help of extrusion they are blown onto a rotating spindle. The entire process is programatically controlled. There are numerous types of grades of melt blown filters available in the industry. The best filters are the ones that offer higher efficiency (i.e. removal rate), longer operational life, and minimum leachables.

Pleated Cartridge Filters

These filters are produced from pleated sheets of filter media and what they generally do is surface filtration. They offer higher efficiency and higher flow rate. Lately new kind of pleated filters have been developed which utilize thick media for filtration; these kind of filters offer both surface filtration and depth filtration.

Sintered Cartridge Filters

Sintered cartridge filters perform depth filtration, and can be either metallic or polymeric. They are produced from fine particles of the desired material. The particles are moulded into a solid cylindrical element. These filter elements are very robust and are always capable of handling very high differential pressures. Their resistance to heat and several chemicals would be based on the material used in the production.

Wire Mesh Cartridge Filters

Wire mesh is defined as “An electric fusion welded prefabricated joined grid consisting of a series of parallel longitudinal wires with accurate spacing welded to cross wires at the required spacing.” (Source: Wikipedia). So, what this filters have are layers of this grid and fluid is forced to traverse through the tortuous path created by these layers. The suspended solids, of certain sizes, get trapped during the course. There are also pleated wire mesh cartridge filters which are constructed from the pleated grids. They offer higher flow due to larger surface area.

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