Cartridge filters are tubular-shaped filters used in various industries to meet a broad range of filtration needs, from primary to fine filtration.
In this blog, we will explore in detail what a cartridge filter is, covering:
Working Principle of Cartridge Filter
According to the different working principles of filtration, cartridge filters can be divided into two types: surface filtration and depth filtration.
Surface filtration
Surface filtration, as the name implies, is to limit pollutants or solid particles to the surface of the cartridge filter.
The pore size of the cartridge filter is smaller than the size of the contaminated impurities, and larger than the size of the medium allowed to pass.
After using the surface filter for a period of time, its surface will be filled with pollutants and the filtering effect will be limited. You need to clean it before you use it again.
Depth filtration
Depth filters are made of multiple layers of woven metal or powdered metal to create a tortuous path for pollutants or impurities, thereby blocking them inside the filter.
These depth filters are usually made of stainless steel, which has good corrosion resistance and can be cleaned repeatedly for a long time. Common ones are sintered filters, wire mesh filters, ceramic filters, string wound filters.
Types of Cartridge Filters
Pleated Cartridge Filter
Pleated filter cartridge is a surface filter, which is composed of the support layer and filter layer connected together.
The pleated appearance can increase the surface area and can capture a large number of pollutant particles.
Due to its support structure and large surface area, it is suitable for high pressure or high flow rate applications, such as air purifiers, air conditioning equipment.
Melt Blown Filter Cartridge
Melt blown cartridge filter is a multi-layer structure depth filter made of heat-bonded polypropylene fibers.
During the manufacturing process, polypropylene is heated to the melting point through an extruder and then melt-blown onto a rotating shaft to form a cylindrical filter element.
The filtration efficiency of melt-blown filter elements is higher than that of wire-wound filter elements. They can achieve fine filtration, effectively filtering particles as small as 0.3 μm.
Melt blown polypropylene filter is commonly used in drinking water purification, food and beverage industry, pharmaceutical and chemical industry.
Sintered Filter Cartridges
Sintered filter cartridges are made of metal powder as raw material and are sintered at high temperature. The interior of sintered filter cartridges is porous and can effectively filter various pollutants. And the filtering accuracy of sintered filter cartridges is controllable. They usually made of stainless steel, titanium alloy or nickel-based alloy, with good high temperature resistance up to 930℃, high compressive strength, and excellent corrosion resistance.
Common sintered filter cartridge materials are:
- 304L stainless steel
- 316L stainless steel
- 310S stainless steel
- Inconel 600
- Inconel 625
- Monel 400
- Titanium
String Wound Cartridge Filter
String wound cartridge filters are also a type of depth filter, consisting of a continuous fiber string tightly wound around a central core.
String wound cartridge filters have gradient density, with the outer layer capturing larger particles and the inner layer capturing finer particles, with a wide filtration range.
The string of a string wound cartridge is usually made of polypropylene, cotton, or nylon, and the filter core is usually made of polypropylene or stainless steel.
Wire Mesh Filter Cartridge
Wire mesh filters are made of one or more layers of woven metal, usually stainless steel, bronze or monel. These wire mesh filters are available in a variety of mesh sizes to provide coarse to fine filtration, usually 1 to 500 microns.
Wire mesh filters are available in a variety of weaves, including plain weave, twill weave, Dutch weave, rectangular weave, etc.
Applications of Cartridge Filters
Water Purification
Pleated filters have a larger surface area and a high dirt holding volume, and can filter sediments, suspended particles, etc. in the water. String wound filters can achieve fine filtration below 1 micron, and are also an ideal solution for pure water filtration.
Chemical Industry
The chemical industry often requires filters to have good corrosion resistance, high compressive strength and long service life.
Sintered filter cartridges and wire mesh filters are usually made of stainless steel, monel or titanium alloy, and have a wide range of filtration accuracy options to meet various filtration needs in the chemical industry.
Mechanical Industry
Metal cartridge filters can effectively remove impurities or contaminants from lubricating oils and hydraulic oils used in the mechanical industry to ensure the smooth operation of equipment.
Medical Field
Cartridge filters, such as sintered metal cartridge filters, melt blown cartridge filters have high filtration accuracy and are suitable for particles such as microorganisms and bacteria.
FAQ
What the Differences between Cartridge Filters and Bag Filters?
Bag filters are oblong fabric or felt bags, while cartridge filters are cylindrical and typically made from pleated metal, woven metal, or powdered metal.
Cartridge filters function as both surface and depth filters, with most serving as depth filters. In contrast, bag filters are primarily surface filters.
Bag filters are ideal for applications with lower filtration accuracy requirements and ample space, such as factory air purification.
Cartridge filters, with a broader range of filtration accuracy, are used in more diverse fields, including pharmaceuticals, the food and beverage industry, machinery, and chemical processing.
How to Clean Metal Cartridge Filter?
You can clean metal cartridge filters using the following methods:
- Ultrasonic Cleaning: Start by heating the metal cartridge filters in a heating device for about 30 minutes to an hour. Then, place them in an ultrasonic cleaner for approximately 30 minutes.
- Chemical Flushing: Soak the filters in a suitable chemical solvent to dissolve and remove any contaminants.
- Thermal Cleaning: Since most metal cartridge filters are made from high-melting-point metals like stainless steel, titanium alloy, or nickel alloy, you can burn off the pollutants inside without damaging the filter.
These cleaning methods will help you maintain the filters’ efficiency and extend their service lives.
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