Cartridge Filters Working Principle

In industrial filtration, filter cartridges play a crucial role in maintaining process cleanliness and high-quality outputs. But what exactly are filter cartridges, and how to use this type of filters in filtration solutions? This blog gives the definition of filter cartridges, their working principle, applications and its types.

What is a Cartridge Filter?

A cartridge filter is a device used to remove impurities and particles from liquids or gases. It is placed inside a filter housing. The fluid enters the housing through the inlet nozzle, and with the help of pressure, it passes through the cartridge. The cartridge traps the contaminants, separating them from the fluid.

It has a simple cylindrical or pleated filter inside a casing made of materials like polypropylene, PTFE, or stainless steel. The micron rating shows the smallest particle the filter can trap—nominal filters catch over 99% of particles, while absolute filters trap all particles below their rated size. As the fluid flows through, the filter captures impurities. Cartridge filters are commonly used in industries for effective filtration. The tubular design seals better and reduces the chance of contaminants bypassing the filter compared to flat filters. Using multiple cartridge filters also makes it easier to replace only the damaged ones, while flat filters need complete replacement if damaged.

Working Principle of Cartridge Filters

The working principle of a cartridge filter is based on the physical process of filtration, which separates solids from liquids or gases by passing them through a porous medium. The filter element, typically made of materials like paper, cloth, or powder sintered media, or even from glass fibers, serves as this medium. When contaminated fluid enters the cartridge filter through an inlet port, it flows through the filter element's pores. Solid particles larger than the pores are trapped on the surface or within the fibers of the filter element, a process known as mechanical filtration. 

As more fluid passes through, trapped particles form a filter cake layer on the surface, enhancing the filter's ability to capture even smaller particles through depth filtration. Over time, the accumulation of particles clogs the filter element, reducing its efficiency. To maintain effective filtration, the filter element must be periodically replaced or cleaned. This straightforward yet effective process ensures that impurities are removed from the fluid, with clean liquid or gas exiting through the outlet. The choice of filter element material and pore size depends on the specific application and desired level of filtration. Regular maintenance, such as replacing of the filter cartridge is essential to ensure the filtration system continues to operate effectively. 

What are the two categories of cartridge filter?

Cartridge filters are divided into two main types based on how they work: Surface Filters and Depth Filters. The table below shows the key differences between them:

Types of Cartridge Filters

Cartridge filters come in various types, each suited for different applications based on their construction and filtration mechanism. Key types include:

1. Pleated Filters: Designed to maximize surface area, making them ideal for high flow rates and efficient filtration in industrial water and HVAC systems. The high surface area also results in a lower pressure drop.
2. Membrane Filters: Utilizing semi-permeable membranes for high-purity applications in pharmaceuticals and food processing.
3. Activated Carbon Filters: Effective for removing impurities and odors from liquids and gases, commonly used in water and air purification.
4. Stainless Steel Filters: Designed for high-temperature and high-pressure applications, such as in oil and gas filtration. Stainless steel cartridge filters are also used in corrosive atmospheres in chemical manufacturing and API manufacturing.

Applications of Cartridge Filters

1. Machinery: Maintain fluid cleanliness and reduce equipment wear.
2. Textiles and Printing: Enhance product quality by removing process impurities.
3. Electroplating and Chemical Industries: Purify solutions and safeguard processes.
4. Natural Gas Processing: Remove contaminants to ensure clean fuel.
5. Coatings, Paints, and Inks: Maintain product consistency.
6. Biotechnology, Pharmaceuticals, Food, and Beverage Sectors: Ensure high levels of purity and safety.
7. Automobile Manufacturing and Electronics: Maintain clean fluids and protect sensitive components.

Conclusion

Cartridge filters are essential for filtering and purifying liquids and gases in many industrial and commercial settings. They come in different designs and work in various ways to meet a wide range of needs, from large industrial processes to precise applications. Knowing the different types, how they work, and where they are used helps in choosing the right filter for each job. Regular maintenance and timely replacement are important to keep the filters working well and efficiently.