How many filters will be needed in my process?

In industrial processes and fluid management, the efficiency of a filtration system directly impacts the quality of your end – product. A common headache for many: installing a filtration setup that either misses purity goals or incurs extra costs due to over – engineering.

When seeking the ideal filtration solution, customers often start with a basic yet crucial question: “How many filters do I need?” The answer isn’t simple, as it involves multiple overlapping factors. Each filtration process is unique, considering diverse fluids, standards, and batch – to – batch contaminant variations. So, the first step is gathering fluid info and desired outcomes.

Thankfully, filtration experts can guide you to the right number of filters, optimizing your system and saving costs. Read on to learn more about making the best filtration choices.

Fluid characteristics

Fluid characteristics play a pivotal role in determining the number of filters required. First and foremost, the viscosity of the fluid is a key factor. Highly viscous fluids, such as certain industrial lubricants or thick syrups in the food industry, are more challenging to filter. They tend to flow more slowly through the filter media, which may necessitate a larger number of filters or filters with a larger surface area to ensure an adequate flow rate.

Secondly, the particle size distribution within the fluid matters a great deal. If the fluid contains a wide range of particle sizes, from very fine particles to relatively large ones, a multi-stage filtration system with different filter pore sizes may be needed. This often means using more filters to effectively capture contaminants at various levels.

Moreover, the chemical composition of the fluid can impact filter selection and quantity. Aggressive chemicals, like strong acids or alkalis, may require filters made from specialized materials that can resist corrosion. In some cases, the chemical reactivity of the fluid might cause clogging or degradation of the filter media more quickly, indicating the need for additional filters to maintain continuous operation.

Identify the type of filter required

Choosing the right filter for your application ensures effective filtration and helps meet your specific requirements. The type of filter you need depends on your filtration objectives, the fluid characteristics, and the nature of the contaminants you aim to remove.

1. Understanding Filter Cartridges and Micron Ratings

Filter cartridges are versatile filtration tools made from various materials and available in different sizes. They are designed to remove solid contaminants from liquids. A key factor in filter selection is the micron rating, which determines the particle size a filter can retain.

Micron Rating Examples:

• 03 um: Used for retaining Acholeplasma laidlawii.
• 10 um and 0.22um: Meet FDA sterilizing-grade filter standards for capturing Brevundimonas diminuta.
• 45 um: Targets Serratia marcescens.
• 65 um: Filters out Saccharomyces cerevisiae.

2. Filtration Objectives and Functions

Your filtration objectives will dictate the type of filter you need. Common filtration functions include:

• Particle Removal/Clarification: Captures solid contaminants of varying sizes.
• Bacteria Reduction/Control: Requires pore sizes that can retain microscopic organisms.
• Sterile Filtration: Designed to ensure microbial control, often using sterilizing-grade filters.

3. How Filters Work and When to Replace Them

During operation, contaminants are trapped either on the inside or outside of the filter element, depending on its design. Over time, as more particles accumulate, the pressure difference across the filter increases. Once this difference exceeds a certain point, the filter must be replaced or regenerated to prevent breakthrough or flow restrictions.

4. Choosing the Right Filter

The size of the contaminants and the desired retention level are critical factors in filter selection:

• For general particle removal, a coarser filter may suffice.
• For sensitive applications, such as pharmaceuticals or sterile processes, membrane pleated filterswith finer pore sizes (e.g., 0.22 um) are necessary.
• Consider fluid properties like viscosity and chemical composition to ensure compatibility with filter materials.

Filter pore size: Nominal versus Absolute rating.

As mentioned earlier, the pore size of a filter is determined by the particle size it aims to capture. Manufacturers typically rate the effectiveness of a filter’s pore size as either Nominal or Absolute, depending on your filtration goals.

• Nominal Ratingindicates the average particle size that a filter can capture, with a typical efficiency of 60-90%. It represents the filter’s ability to block contaminants, but particles smaller than the nominal size may still pass through. This rating is commonly used for depth media filters in applications where complete filtration is not essential.
• Absolute Ratingrepresents the maximum particle size that will be blocked by the filter, with an efficiency of 99.999%. This rating is typically used for membrane filters, ensuring nearly complete removal of particles larger than the specified pore size. It’s ideal for applications requiring precise and reliable filtration, such as in pharmaceutical, food, or water treatment industries.

Materials of construction

The material chosen for filter construction is one of the most important factors influencing its performance, durability, and overall compatibility with the specific application.

The right material ensures that the filter can effectively handle the operational conditions, including temperature extremes, chemical exposure, and mechanical stress. Materials such as polypropylene, stainless steel, and Teflon are commonly used depending on the environment and the contaminants being filtered.

For instance, polypropylene is lightweight, cost-effective, and widely used for general filtration applications, especially in water treatment and food processing industries. It is resistant to many chemicals and provides a good balance between performance and cost. Stainless steel, on the other hand, is ideal for applications involving high pressures or temperatures, such as in the oil and gas industry, chemical processing, or high-flow liquid filtration systems.

Flow rate requirements

Flow rate is a key factor when choosing a filter. It represents the volume of liquid or gas passing through the filter within a set time, usually measured in liters per minute (LPM) or gallons per minute (GPM). The filter must manage the desired flow rate while maintaining optimal filtration performance. A flow rate that’s too high can cause excessive pressure drop or inadequate filtration, while a filter rated too high can be inefficient and wasteful.

In continuous processes, the required fluid volume is easy to determine. It’s advisable to aim for a flow rate slightly higher than the minimum requirement to handle potential fluctuations in feed fluid, ensuring smooth operation.

For batch processes, the flow rate depends on the batch size and processing time. For example, filtering a 5,000-liter batch in 8 hours requires calculating the appropriate flow rate. Accurately sizing the filter improves both filtration efficiency and overall performance, minimizing disruptions or inefficiencies.

Target filter change-out frequency

The frequency of filter replacement depends on factors like the type of contaminants, filter material, and system capacity. Scheduling regular filter change-outs ensures reliable operation, prevents clogging, and keeps the filtration process running efficiently. When replacements are planned on a set schedule, the required number of filters can be calculated based on flow rate, production volume, and the system’s operational requirements over a given period. Multiplying this by the number of scheduled changes per year gives an estimate of the total filters needed annually.

For processes relying on filter lifespan rather than fixed intervals, factors such as contamination levels, fluid viscosity, and filter size determine when a change-out is necessary. Testing these variables helps estimate filter life expectancy, allowing businesses to create a replacement schedule based on actual usage. Once the expected filter life is understood, filters can be planned for quarterly or annual replacement, ensuring reliable performance and cost efficiency.

Conclusion

Determining the number of filters needed for a specific application involves a detailed analysis of the process and its unique characteristics. In some cases, a straightforward evaluation of the process can provide the answer. However, for more complex situations, additional testing may be necessary to optimize filter selection and accurately determine the required quantity.

At Brother Filtration, we go beyond just offering products—we work closely with you to ensure your filtration objectives are met, providing tailored solutions to optimize your entire filtration process. Our team is here to support you every step of the way. Contact us today for personalized assistance and expert guidance!