What are micron and beta ratings in filtration?


In the world of filtration, there can be a lot to get to grips with when it comes to understanding filtration ratings – FilterFinder know that better than anyone! With over 50 years of experience in the industry, FilterFinder has a wealth of expertise that can teach you everything you need to know about choosing the right filtration solution.

With filtration being a critical activity for many industrial or manufacturing organisations, it’s vital to choose the right micron and beta rating to keep contaminants like dirt, metal shavings and other particulates from circulating inside a hydraulic system and causing damage – but what exactly does this mean? The effectiveness of filtration and separation impacts processes that determine quality standards for your application; therefore, you need to select the right micron and beta rating to ensure the size at which particles are retained by the filter are correct. With that in mind, the key starting point for your filter selection process is the micron rating so you establish which filters have the capabilities you require. Let’s break it down…

What is a Micron Rating?

Micron is short for micrometre – one-millionth of a metre (a minuscule unit of measure to say the least!) The micron rating refers to the aperture size of filter media and is used to indicate the ability of a filter to remove contaminants by the size of the particles. Essentially, the smaller the micron rating, the finer the particulate removed. Let’s put this in perspective – a human hair is between 40 to 90 microns in diameter, bacteria range from 0.5 to 50 microns and particles above 50 microns can be seen by the naked eye. Take a look at the graph below for context.

For example, a 40 micron rated filter will allow larger particles to pass through than a 5 micron rated filter – the smaller the micron rating, the more effective the filter is at removing particles of that micron size. A lot of hydraulic failures are a result of particle contamination which is why it’s critical to specify the micron rating.

Nominal vs Absolute Ratings – What’s the difference?

The most common filter ratings are either nominal or absolute, and each describes the general capacity for the filter to remove particles of the specified size at a specified efficiency. Simply put, a filter with a nominal rating is low efficiency, and a filter with an absolute rating is high efficiency. Nominal ratings indicate the efficiency of about 50 percent, whereas absolute ratings indicate the filter is 99.9 percent efficient at capturing all particles at or above the stated size on each pass.

What is a Beta Rating?

Beta ratings come hand in hand with micron ratings and in fact, can provide more clarity when it comes to measuring media’s efficiency. It’s fine talking about micron sizing, but without a beta rating, manufacturers wouldn’t be able to describe the performance of the media used inside a filter. So what exactly is it and how do you measure it effectively? Well, beta ratio is used to express filter efficiency for a given particulate size. This, in summary, is the number of particles before filtration divided by the number of particles after filtration. Here’s an example:

If a 5-micron filter element has 1,000,000 particles upstream (pre-filtration) and allows 1,000 particles downstream (post-filtration), it’s Beta ratio would be calculated as 1,000,000 (upstream) / 1,000 (downstream) = β1000 or an efficiency of 99.9%.

All in all, beta ratings give us a scientific standard to compare and gauge the filtration quality of elements and they are used to explain the efficiency of filtration for all fluids, oil, diesel, petrol etc; it’s simply a measurement that’s used within the filtration industry. It’s highly important that both the micron rating and beta ratio is matched to the required application to maximise effectiveness and reduce the risk of damage and issues within systems.

For this reason FilterFinder took the decision to only supply our customers glass fibre elements (β1000 | 99.9% efficient) rather than cellulose (β2 | 50.0% efficient) where possible to ensure your system gets the highest quality of filtration it can leading to a healthier and longer lasting hydraulic system.

For further information about micron and beta ratings or to enquire about our filtration services, please contact support@filterfinder.co.uk.

Source: FilterFinder 

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