Filter Cartridges

How do filter cartridges work?

The mechanics of filtration can work in two differing ways and the selection is important for each application:

• Surface filtration: particles are retained on the surface of the filter medium.
• Depth filtration: particles penetrate the filter material and are captured within it.

The performance characteristics of a filter cartridge are determined by both the filter media and the manufacturing method used. Different materials and constructions provide specific advantages depending on the application and process requirements. Polypropylene is one of the most versatile filtration media and is available in wound, meltblown, and pleated cartridge designs. Depending on the required level of filtration, cartridges can be supplied with nominal ratings or with absolute ratings up to Beta 5000, corresponding to a filtration efficiency of 99.98%.

Selecting the right filter cartridge requires careful consideration of the process conditions. Parameters such as temperature, filter surface area, viscosity, operating pressure, flow rate, the nature of the liquid or gas being filtered, and the type and concentration of contaminants all influence the choice of the most effective filtration solution.

Other considerations, including energy efficiency, batch or continuous processing, waste minimisation, and product availability, may also influence the choice of filtration solution. As process criticality increases, so does the importance of selecting the appropriate filter cartridge. For example, in food, beverage, and pharmaceutical applications, absolute-rated filter cartridges with a Beta ratio of 5000 (99.98% efficiency) and bacteriological retention capabilities are often required to meet stringent quality and regulatory standards.

Techno filter range cartridge filters

Techno Filter offers a comprehensive range of filter cartridges with retention ratings from 0.01 to 800 microns.

Our portfolio includes filter cartridges manufactured from a wide variety of materials, including polypropylene, nylon, cotton, glass fibre, PES, PTFE, Ryton®, polyester, stainless steel, activated carbon, and resin-bonded media. We also supply specialist oil-adsorbing filter cartridges for applications requiring the removal of hydrocarbons and trace oil contamination.

Filter cartridges are available in lengths ranging from 2.5″ to 70″ and can be supplied with a wide range of industry-standard end configurations, including single open end (SOE) and double open end (DOE) designs, with or without bayonet fittings.

For applications requiring high flow rates, Big Blue and High Flow filter cartridges can offer significant advantages. Their larger diameter and increased filtration surface area allow higher flow capacities while reducing the number of cartridges required, resulting in lower operating costs, reduced maintenance, and less waste.

We also supply specialist filter cartridges for a wide range of applications, including oil-adsorbing cartridges for hydrocarbon removal, activated carbon cartridges for the reduction of odour, colour, taste, and chlorine, and resin-bonded cartridges for demanding filtration processes.

Techno Filter’s expertise extends beyond filter cartridges. We offer a complete range of filtration products, including filter bags, filter housings, lenticular filter modules, strainers, and solutions for gas and air filtration.

To ensure compatibility with your filtration system, cartridges are available with a variety of standard O-ring materials and configurations, allowing the filter element to be optimally matched to your process requirements.

Connection types

Filter cartridges are generally available in two main end connection configurations. The most suitable option depends on the application requirements and, in many cases, the design of the filter housing.

• Double open end (DOE) – both ends of the filter cartridge are open. Sealing is typically achieved using flat gaskets or O-rings at each end of the cartridge.
• Single open end (SOE) – one end of the filter cartridge is open, while the opposite end is closed. Sealing is achieved by means of O-rings or a gasket at one end, ensuring that all fluid passes through the filter media without bypass.

Double open end

Double open end (DOE) filter cartridges are open at both ends and are commonly used in simple, cost-effective filtration systems. Sealing is typically achieved by compressing gaskets or O-rings against the housing knife-edge seals, ensuring that fluid is directed through the filter media and preventing bypass.

DOE cartridges are available in a variety of configurations, including:

• Double open end without end caps
• Double open end with end caps, available in several sealing arrangements:
  • Flat gasket
  • Flat gasket with an extended core on one end
  • Internal O-rings

The most suitable configuration will depend on the filter housing design, operating conditions, and sealing requirements of the application.

Single open end

Single open end (SOE) filter cartridges are open at one end and closed at the other. They are commonly used in applications where a high level of sealing integrity is required. The O-rings provide a secure seal between the filter cartridge and the housing, preventing fluid bypass and ensuring that all fluid passes through the filter media. Most SOE configurations utilise a double O-ring arrangement, providing additional sealing integrity and reducing the risk of bypass. O-rings are available in a range of materials to suit different process conditions and chemical compatibility requirements.

There are numerous SOE configurations available, with the most common being:

• Code 3 – flat closed end with an external double 222 O-ring configuration at the open end.
• Code 8 – fin (spear) closed end with an external double 222 O-ring configuration at the open end.
• Code 2 – flat closed end with an external double 226 O-ring configuration and bayonet locking mechanism at the open end.
• Code 7 – fin (spear) closed end with an external double 226 O-ring configuration and bayonet locking mechanism at the open end.

The choice of end connection depends on the filter housing design and the level of sealing security required by the application. Many other end cap configurations are available, including OEM-compatible and retrofit designs.