Learn the fundamental aspects of filtration technology.

As introduced in our Principles of filtration blog, we will explain some of the fundamental aspects of filtration technology and how they relate to each other as well as to your application. Filtration media have many different properties that impact its performance in certain applications. 

When selecting the best filter media for your application, consider the following important properties:

• Depth vs. Membrane Filtration
• Filter efficiency
• Hydrophilic vs. hydrophobic
• Pore size rating
• Chemical compatibility
• Flow rate and throughput
• Extractables
• Binding
• Thermal stability

Filter efficiency

Filter efficiency measures the percentage of particles and/or bacteria which are removed from the fluid by the filtration membrane. In the filtration of liquids, filter efficiency is given based on particles at or above a certain diameter in size. In gas filtration, efficiency is stated as including all particles, including those at the most penetrating particle size.  This efficiency is reported in terms of the percentage removal of the particles by weight, which does not reveal the number of particles that may pass through the membrane. This is a type of nominal filter rating. For high-efficiency filters, this is often replaced by a beta rating. Membranes rated as 1µm or finer are often rated using titer reduction values or log reduction values.

Do you know what efficiency is required in your application?

Filter life

Filter life is a measure of how long a membrane will last before requiring replacement or cleaning. It can be stated either in terms of time (e.g., 30 days between changes) or volume of fluid filtered (e.g.,10,000 liters processed between filter changes). A filter material’s actual life will depend on the particulates and conditions it is exposed to in usage. Filter life ratings from lab testing with standard contaminants can be used for comparison, but do not necessarily predict actual service life. To predict actual life, testing with the application fluids under operating conditions is required. Typically, the useful life of a membrane can be determined by a two-to-four-fold increase of differential pressure in a constant flow system or a drop in pressure of 50-80% in a constant pressure system.

Explore our OEM membranes filtration solutions

If you have questions related to this content or other filtration concepts or how they apply to your specific application, please contact us.

FAQs

1. What factors should be considered when selecting filter media?

   Important properties include depth vs. membrane filtration, filter efficiency, hydrophilic vs. hydrophobic characteristics, pore size rating, chemical compatibility, flow rate, extractables, binding, and thermal stability. 

2. What is filter efficiency and how is it measured?

   Filter efficiency measures the percentage of particles removed by the membrane. For liquids, it is based on particles at or above a certain size; for gases, it includes all particles, even the most penetrating size. Efficiency is reported by weight and may use nominal ratings, beta ratings, or log reduction values for finer membranes. 

3. What is filter life and how is it determined?

   Filter life indicates how long a membrane lasts before replacement or cleaning. It can be expressed in time or volume processed. Actual life depends on application conditions and is typically predicted by pressure changes during operation. 

4. Why is chemical compatibility important in filter media selection?

   Chemical compatibility ensures the filter material can withstand exposure to application fluids without degradation, maintaining performance and safety. 

5. How does pore size rating affect filtration performance?

   Pore size rating determines the size of particles retained by the membrane, impacting efficiency and suitability for specific applications. 

Author bio

Jacques Hestres, Manager for Media and Membrane

Focusing primarily in Medical OEM applications. Throughout his over 25-year career, Jacques has held various positions in Customer and Technical Service, Operations Planning, and Product Management. This experience has given him the knowledge of the products, the manufacturing processes used to produce these materials, and an understanding of applications where these are used. Jacques holds a Bachelor of Science Degree in Biology from the University of Puerto Rico.