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Probat’s safety first approach

From the March 2017 issue.

German process machinery manufacturer Probat places safety of its machinery at the heart of its design process.

Probate water rack

As a leading manufacturer of coffee roasting and processing machinery, Probat is always pushing its machines to do more and to work better than the machines that came before.

But pushing its machines to perform to their highest capability also means testing their limits, and Probat’s Director of Product Technology and Research and Development Thomas Koziorowski knows that extra precautions must be taken in order to do this safely.

“Due to the added flexibility that we give to our customers to play with the different parameters of their equipment, there is always the possibility that this can lead to critical situations, such as if there is a lot of excess gas from the roasting or something like that,” Koziorowski tells Global Coffee Report.

“In order to make sure this does not create an issue for people’s safety, we directly integrate measuring components and reaction components into the equipment that can give the operators pre-warnings if they are headed in a direction that could be critical. There are more than 150 different points that we build in that can act together to keep the equipment safe – from pre-warning up to stopping the process.”

Koziorowski says that the safety features in a modern Probat machine are much like the features you see in a modern car.

“Mechanisms that can pre-warn you when you’re about to get into an accident – these are the kinds of things we transfer into the roasting process,” he says.

With a global network of customers ranging from small shop roasters to some of the world’s leading multinational coffee brands, Koziorowski says that safety is a key element in the design of all of Probat’s machines.

“The safety of operators, service personnel and the equipment has always been a high priority for Probat,” he tells GCR. “For centuries, we have been doing risk assessments for our products and design safety features to avoid these risks. Increasing safety requirements and growing demands on flexibility of machines forced us to assess the safety of our products from different perspectives.”

Koziorowski says there are three most common sources of risks: the mechanical design, the process itself, and the layout of plants.

“Risks stemming from mechanical design, for example, result from moving parts in the machine, which at the utmost can be covered to avoid damages to anyone and anything,” he says. “The process is more complex as multiple possible situations have to be considered, such as fire in a roaster, which can be caused by various combinations of parameters and faulty operation.”

Risks from layout are due to the arrangement of components.

“All points of maintenance have to be reachable and should allow safe maintenance. No parts of the plant are allowed within range of emergency ways.”

While risks with a high severity and a low chance for people to avoid them, such as explosions and fire, are a key focus, they are not handled differently by the designers, Koziorowski says.

“In high temperature applications such as roasting always lies the danger of fire with further consequences. Last but not least, operator errors have to be excluded just as risks evolving from insufficient maintenance by the operator.”

Probat PLC

Koziorowski says the procedure of risk assessment nowadays is much more structured and standardised to guarantee a consistent quality and to cater to the increased range of potential risks.

“Whereas the design of the safety features follows [to the highest extent possible] current internationally-recognised standards, such as the International Electrotechnical Commission’s (IEC) 62061, which didn’t exist to that extent 15 years ago.”

While the safety of people is the primary object, preserving the machinery and the product inside is also a key consideration.

“In many cases, this can be directly combined with the safety of personnel,” Koziorowski says. “If possible, we also try to avoid loss of coffee. Another domain we focus on is the user friendliness of the safety features. We do not want to limit the usability of our products and therefore look for easy to maintain designs. In this process we consider different situations and phases the machine can be in, such as installation, operation and maintenance.”

While safety reviews of the roasting systems have always been part of the design process, a vital change emerged when the European machinery directive was issued. In combination with respective standards, this led to the application of certified safety controls.

“Depending on the overall risk potential, which is derived from the severity, the chance for people to withdraw or avoid the risk, the frequency people are exposed to the potential risk, and the probability of occurrence, nowadays there are different requirements on safety features,” Koziorowski says. “Especially electrical, electronic and programmable electronic safety features, which are used to mitigate risks with a high potential, today have to achieve a certain Performance Level or Safety Integrity Level.”

These categories represent certain probabilities of failure of a safety function. That is why there is a stronger focus on the parts selection and the correct use and installation of these parts. The probability of failure for the entire safety function achieved has to be verified by calculation. An insufficient part diminishes the quality of the entire safety function. These requirements result from new and modified standards, such as the IEC 62061, and especially as a Europe-based norm, the EC directives of the European Union. These changes in the legal requirements also triggered the development and certification of Programmable Logic Controllers (PLCs) as components for safety functions.

“The safety PLC allows us to realise more complex and sophisticated safety features than ever before,” Koziorowski says. “Whenever a safety PLC is economically sensible, we focus on realising as many safety features as possible through this component.”

Koziorowski explains that the safety PLCs allows Probat to ensure a sufficient purging of even the most complex roasting systems despite of the number of bypasses and flaps.
“This provides us and our customers with great flexibility,” he says.

Another recent development is the infrared camera, which is used to monitor the entire cooling area instead of a thermocouple, which can only measure the temperature on a spot of the cooler.
“With this camera, we can reliably identify hot spots in the cooler,” Koziorowski says. “The online carbon monoxide monitoring unit, even though standard for several years, is one of the most important safety features since it prevents explosions, which can otherwise occur in recirculating systems.”

While all of these technologies play critical roles in ensuring the safe operation of Probat’s machines, Koziorowski says that the main element is the mindset that the company itself brings to the design process.
“Safety is now part of our company DNA,” he says.

“For us, the dual control principle applies and all installations have to undergo safety checks. Without having been subjected to comprehensive safety checks, no roaster gets handed over to the customer.

“We always strive for the safest machines and most recent safety technology. If we narrow it down to technologies, it is definitely the safety PLC, which has brought us and our products, especially roasters, forward. Complex logics and analyses can be done, which weren’t possible before. This technological basis has a great potential for further application developments.” GCR

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