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FLOW & LEVEL CONTROL


ACCURATE DOSING INTO DOUGH MIXTURES


An industrial bakery has increased product quality and reduced production costs after installing high accuracy ball valves from Bürkert


demands accurate doses of additives into dough mixtures. These additives are essential for the baking process, and impact attributes such as taste and shelf life. The liquid additives include water, vinegar and oil, as well as ingredients suspended in liquid solutions, such as yeast. Accurate dosing is a vital


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aspect of industrial baking, and imprecise levels of ingredients can impact product quality, including taste, form and shelf life. This reduces efficiency with a higher level of inferior product and wastage. The unnecessary addition of expensive ingredients also increases the cost of production. The bakery works with 500kg batches


of dough, while adding ingredient quantities as little as 100g. As a result, an error of just 3-4g can significantly impact the end product. The bakery was equipped with an automated system, but it was providing insufficient accuracy. The primary cause was the system’s angle seat valves that generated excessive dosing volume as well as variability, creating inconsistent dosing. As a result, the bakery and its engineering partner turned to Bürkert to upgrade the valve system. The bakery’s engineering team integrated its


PLC-based system with a suite of Bürkert electromotive ball valves with high-speed actuators in ½” and 1” dimensions. Various spring


t a large UK industrial bakery, that produces a wide variety of products, the plant’s liquid improvement system


combinations were tested with the fast acting, rapid-closing valves before the optimum shut- off rate was achieved. The result was vastly improved flow


regulation, enhancing the speed, accuracy and consistency of dosing control. For the bakery, this meant an increase in product quality and a reduction in production costs. Kieran Bennett, Industry


Account Manager, Food & Bev, Bürkert, said: “As a result of the improvement to product quality and the


production process itself, the bakery has now implemented the system on wider dosing


applications across its plant.” The primary challenge in


establishing dosing accuracy came from the type of valves originally installed. Angle seat valves were previously specified but they didn’t


provide sufficiently fast or consistent closure rates to ensure flow control accuracy. The valves’ seats had also deteriorated over


time and changed their form, which meant an inconsistent flow rate that was exacerbated under high flow conditions. A previous attempt to improve accuracy by installing stroke limiters to restrict the valves’ orifice sizes was unable to resolve the issue. Analysing the situation, Bürkert advised that


integrating a ball valve and actuator combination would achieve a significant increase in dosing accuracy. The valve’s fast-


closing action could provide high-speed control over the inflight allowance, with rates of accuracy lower than +/- 1g from a 100g ingredient dose. Predictability of the valve closure rate is an


important factor for dosing consistency, but it had to be matched with an impermeable barrier. Seepage when the valve is closed also impacts dosing accuracy. The ball valves’ optimum sealing prevents any penetration even against the most aggressive solutions. A secondary benefit of the valves’ fast


closure rates is that if the system experiences a shutdown due to an unexpected power loss, the closure rate is extremely rapid. This secures the media and prevents unwanted excess flow. Within the bakery, orifice plates have also


been installed to restrict flow to specified areas. These restrictors aid control accuracy, stabilising flow and reducing variation. Combined with the new valves, hammer effect has also been removed. “With stainless steel bodies and highly


durable seals, the bakery can confidently expect a typical lifetime of 10 years or more from Bürkert’s ball valves,” said Bennett. High accuracy valve control has not only


decreased the cost of production, but product quality has also been optimised. This has increased value for supermarkets and retailers, and ultimately, has improved satisfaction for consumers.


Bürkert Fluid Control Systems www.burkert.co.uk


DECEMBER 2022/JANUARY 2023 | PROCESS & CONTROL 17


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