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Why is Ra-value important for products in a cleanroom environments?

In industries and environments with high sanitary standards, such as pharmaceutical-, food processing-, or cleanroom applications, it is necessary to minimize the potential for bacterial growth and cross-contamination. Products used in daily operations, such as extraction arms, need a smooth, easy-to-clean surface that is resistant to different substances and acids.

In order to meet sanitary requirements and demands set by authorities, companies often choose products that are made of stainless steel. This is due to its corrosion resistance and durability, but not least, the ease of cleaning, a characteristic of products with a low Ra-value.

So, what is Ra-value?

The roughness of the surface is essentially what Ra-value refers to. “Ra” stands for the arithmetic average roughness, which is a measure of the deviations from a true plane surface. A lower Ra-value indicates a smoother surface, and a higher value indicates a rougher one.


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One may think that the lower the Ra-value, the better, but this is false. In reality, the best conditions for sterilizing and cleaning are achieved when the Ra-value of the surface is between 0.25 and 0.60 µm. It is, in short, the sweet spot.

Fumex PSS has a Ra-value of ≤ 0.6

Fumex PSS is one of our extraction arms in stainless steel, and it has a Ra-value of ≤ 0.6. With such a smooth surface, it becomes easy to clean the arm, as well as maintain a safe and sterile environment where neither dirt nor toxins can be found. The PSS is also the first extraction arm on the market with a hermetically sealed profile, making it even easier to keep clean.

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The extraction arm is also equipped with our quick connection system FUMEX Q-MaiD™, which makes it easy to disconnect the hose, to be able to sterilize and clean the supporting parts and hood of the extraction arm, as well as the hose.

If you want to invest in an extraction meeting high sanitary standards, please download the product brochure for Fumex PSS or contact us for more information.