QMT Features: April 2017
A tasty beer requires a smooth finish
Surprisingly enough, a surface roughness tester is a key ingredient in a good pint

Even the smallest traces of microbiological contaminants can multiply during the brewing process, so it is vital to maintain highest levels of hygiene to produce consistently high quality beer. To help ensure adequate levels of cleanliness, stainless steel remains the material of choice for brewing-plant. The specific alloys that are most often used are AISI 304 and 316, which are very corrosion resistant and are essentially inert to beer.

However, if the surface finish is not up to scratch problems can, and will arise. So, when ordering new plant, brewers need to make sure that the surface is polished and finished to specification. Craft beer maker Brewdog, for example, is scrupulous in ensuring the quality of its plant.  Located on a 5.5-acre site in Ellon, North of Aberdeen, Brewdog’s plant is a state-of-the-art eco brewery and is one of the most technologically advanced and environmentally friendly breweries in the world.

Although there are a relatively small number of micro-organisms that can affect the quality of beer, they can have a massive negative effect on the end product – radically altering the taste of the beer and potentially resulting in expensive losses for the brewer.

Plant Engineer Niall Murphie explains: “As Brewdog is constantly increasing our capacity we regularly source new processing equipment. To help prevent hygiene problems - all stainless steel vessels, fabricated pipework and equipment we purchase has its surface finish check to ensure it conforms to our stated hygiene standards.
“As our previously used surface finish checking methods were somewhat subjective and could lead to differences of opinion with our suppliers, we recently searched for?a more objective means of measuring this important parameter. Having considered several options, we purchased a Surftest SJ-210, Portable Surface Roughness Tester from Mitutoyo. As our new surface tester is calibrated and its results are traceable to national standards, our suppliers see its findings as being unbiased and factual.”

He continues: “Now, in addition to using the new, Mitutoyo instrument throughout our brewing plant, its light weight and portability allows us to bring it to our fabrication suppliers and to check that all stainless steels fabrications conform to our specifications. In addition to setting the instrument to a nominal surface finish figure of, for instance 0.8 µm Ra, we also apply acceptable upper and lower tolerance limits. This ensures that pass/fail results are displayed immediately after completion of a measuring routine. As we use the Surftest SJ-210 in some difficult to access areas it helps that its results are displayed on an easy to read back-lit LCD.

As well as improving our accuracy capability in this critical area, our new Mitutoyo instrument has also increased our speed of stainless steel surface inspection.”

The Surftest SJ-210 Portable Surface Roughness Tester, as purchased by Brewdog is a portable surface roughness tester that is able to operate independently of mains power and to make accurate measurements?on almost any part of a workpiece of practically any?size.
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