Depth Cartridge Filters

Depth filters (also known as spun or meltblown filters) are normally used when there is a broad range of contamination to be removed, or when the range is an unknown. They're used to remove particulate and contamination, such as hazes, gels, and agglomerations, from liquids throughout the process industries.

For example, a 1 micron nominal depth cartridge filter, prevents damage, blockage, or wear and tear of process pipework and equipment - valves, heat exchangers - that process liquids pass through. And a 5 micron absolute depth cartridge filter ensures the visual clarity of liquids in beverage applications. PoreFiltration offers a full product range for new and retrofit applications including both absolute and nominal ratings.

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What is depth filtration?

Depth filtration is a method of removing particles from a fluid by passing it through a porous medium where particles are trapped throughout the entire depth of the filter material, not just on the surface, allowing for high dirt-holding capacity and efficient removal of a wide range of particle sizes.

How does a depth filter work?

As fluid flows through the filter, particles encounter a complex network of fibers within the media, causing them to be captured and retained through a combination of mechanical sieving, adsorption, and electrostatic attraction, with larger particles caught at the beginning and smaller ones deeper within the filter.

What are they key advantages of depth filtration?

High dirt-holding capacity: Can trap a large volume of particles before becoming clogged.

Cost-effective: Generally cheaper than membrane filters.

Flexibility: Can handle a wide range of particle sizes and contaminant loads.

What are the disadvantages of depth filtration?

Less precise filtration: Will not remove very small particles and microrganisms as effectively as a membrane filter.

Not microbially retentive: Depth filter are used to remove hard particulates from a fluid stream. If a microorganism is retained it has the possibility that that microorganism will grow-through the depth filter structure and then enter back into the downstream liquid.

What types of filter media are used in depth filtration?

Polypropylene fibres: Offer good chemical resistance and are often used in industrial applications.

Nylon and Polyester: Offers excellent chemical and temperature resistance. Often used with high viscosity liquids where temperature is used to reduce the fluid viscosity.

How is a depth filter typically specified?

Either by Absolute rating (Beta Ratio 5,000 / Efficiency 99.98%) for complete particulate removal or Nominal filter rating indicating the particle size that is removed at a certain percentage efficiency (usually between 95 to 99.5%).

Read more about Absolute Vs Nominal ratings in depth cartridge filters HERE.

When would you use a depth filter instead of a membrane filter?

When dealing with high contaminant loads in a fluid.
When cost-effectiveness is a primary concern.
For pre-filtration before a membrane filter to protect the membrane from clogging.

What are some common applications of depth filtration?