The Basics of Micron Ratings

The micron rating of a filter is a fundamental specification in any filtration system, as it defines the size and quantity of particles that can be removed from a liquid. In industrial-strength filtration, understanding micron ratings allows for the selection of the appropriate filter based on the specific requirements of the application. Below, we will explain commonly used micron ratings and their relevance in various industries, helping you make an informed choice.

How does a process filtration filter work?

In both everyday life and industrial applications—whether handling water, oil, chemicals, or food and beverages—liquids often contain solid contaminants. Solid-liquid separation safeguards downstream operations while preserving the desired liquid quality.

Filters work by capturing and retaining solid contaminants as liquids pass through the filter media. They can be made from a variety of materials and come in several formats, including cartridges, bags, and sheets. These filters fit within a permanent housing and are designed for easy replacement.

Selecting the right filter can be challenging, as it involves considering various factors such as flow rate, pressure, temperature, and chemical compatibility. Brother Filtration offers a comprehensive range of filters, including depth filter cartridges, pleated filter cartridges, and membrane pleated filter cartridges, tailored to meet the specific needs of your filtration process.

What is a micron rating?

A micron rating indicates the size of particles a filter can capture. For instance, a 5-micron filter blocks particles 5 microns or larger. One micron is one-millionth of a meter. To put it in perspective, human hair is 40-90 microns thick, and bacteria range from 0.5 to 50 microns.

Filters with different micron ratings are designed for varying filtration needs. A 5-micron filter removes most impurities in liquids, commonly used in food and beverage industries. However, filters smaller than 5 microns can clog quickly, so they are often paired with other filters.

10-micron filters are suitable for larger particles but won’t remove bacteria or viruses. They’re commonly used in industries like oil and chemicals, though they can still clog over time.

25-micron filters are used for larger debris, such as particles larger than white blood cells. These filters are efficient in chemical processing and other industries, but they work best when paired with smaller micron filters.

50-micron filters capture visible particles, like sand or hair, and handle large volumes of liquid with minimal clogging. They are widely used where larger debris needs to be filtered without affecting flow.

The Difference Between Nominal and Absolute Micron Rating

Filters are designed to capture different contaminants, and the efficiency of filtration depends on whether a nominal or absolute micron rating is used.

Nominal Micron Rating

A nominal rating reflects a filter’s ability to capture the majority of particles at the specified micron size, usually between 60% to 98%. These filters are commonly used for disinfection, removing particulates, chlorine, chemicals, and improving taste and odor. Carbon filters are often nominal rated.

Absolute Micron Rating

An absolute rating ensures 100% retention of particles at the specified size, with controlled testing conditions. These filters are used in critical applications, like final filtration or sterilization, where complete contaminant removal is necessary. Pleated filters are a common example of absolute rated filters.

Micron Ratings Breakdown

A smaller micron rating means finer filtration, removing more particles. However, fine filters can clog faster in high sediment environments, increasing pressure and reducing flow, requiring more frequent replacements.

In systems with high sediment, multiple filtration stages with varying micron ratings are used to maintain efficiency and extend filter life.

Micron ratings define the particle size that a filter can capture. A smaller micron rating indicates the filter can remove finer particles. Below is a breakdown of common micron ratings and their particle sizes:

Typical micron ratings used by application

Different industries require specific micron ratings to meet their filtration needs. Typical micron-level details for different application scenarios are as follows:

Municipal Water

• 5.0 micron filter controls turbidity
• 1.0 micron filter removes Cryptosporidium
• 10 micron filter protects RO systems.

Spirits Filtration

• 5.0 micron filter optimizes appearance
• Carbon filtration removes color

Coatings, Inks, and Paints

• For solvent-based products, use 1, 5, or 10 micron filters
• For UV-cured types, 1 or 5 micron filters work well
• Water-based types require a 0.2 or 0.45 micron filter with a 1 micron pre-filter
• For pigment-based types, 0.5, 1, or 2 micron filters are effective

Process Water

• 0.2 micron filter is ideal for sterile filtration
• 5.0 or 10.0 micron filters are enough for protection or collection

Parts Cleaning

• For particles, use 1, 5, or 10 micron filters
• For organic substances, a 5 micron carbon filter is effective

Conclusion

At Brother Filtration, we offer an extensive range of liquid filtration solutions, including filter bags and cartridges, with micron ratings spanning from 1 micron to 1000 microns. Each type is available in various sizes to meet different needs.

While we’ve highlighted some of the most common micron ratings, you can find more in-depth details on our product pages. For any inquiries about micron ratings, feel free to reach out to us at [email protected]!