September 2020

35 www.drivesncontrols.com September 2020 FOOD AND BEVERAGE n Marston’s brews up a modern way of checking tank levels S ince 1898, Marston’s Brewery has been producing English ales at its site in Burton on Trent in Staffordshire. Although tradition has much to recommend it when it comes to techniques for producing beer, this is not always the case with process control. Modern options can offer important benefits, as proved to be the case when the company decided to update the level control system on six of its massive bright beer storage tanks at the site, each of which can hold up to 21,000 litres of beer. Before the upgrade, plant operators used to monitor and control the level of beer in the tanks manually with the aid of sight glasses – essentially the same technique that had been used since the brewery opened. But these glasses required regular cleaning, which was an awkward operation, and some were not readily visible, making it hard for the operators to keep track of the levels. As a result, the tanks were sometimes allowed to become completely empty, allowing air into the system and disrupting the operation of the bottling lines. Marston’s decided it was time to upgrade to a more modern and reliable alternative that would allow accurate automatic control of the tank levels and would interface with the plant’s PLC and Scada systems to allow the levels to be monitored remotely. The new systemwould also need to provide clear level indications via digital displays next to the tanks. Marston’s approached the sensor-maker, ifm electronic, which suggested fitting each tank with two flush-fitting hygienic pressure sensors with integral displays, as well as an hygienic level sensor. Choosing sensors with IO-Link interfaces would allow digital process values to be transmitted, simplifying the interface with the existing plant systems. IO- Link would also ensure that the data captured would be transmitted accurately. The brewery uses an Ethernet network with a redundant ring topology to ensure reliability. The new sensors were connected to this via IP65-protected Ethernet interface modules which could be installed in the field without neeing additional protection. The requirement for local displays of the tank levels was satisfied using IO-Link display modules which also connect directly to an IO-Link master port on the AL1121 Ethernet modules, and also needed no extra protection when mounted in the field. Traditionally, the sensors would have been installed on top of the tanks, but in this case, the space above the tanks was limited and difficult to access. It was therefore decided to mount the sensors in the pipes that supply the top pressure to the tanks. They provide identical data in this location, but installation was faster, easier and safer because scaffolding was not needed. Despite the high reliability of modern sensors, Marston’s engineering team wanted to be sure that it would be easy to replace the sensors should this ever prove necessary. This requirement was satisfied not only by installing the sensors at a convenient working height, but also by taking advantage of an intrinsic function of the IO- Link system which allows configuration data to be uploaded directly to the sensors. If a sensor needs to be replaced, the configuration data is sent to the new device via its IO-Link connection. It is then ready for immediate use. The need for inconvenient and time-consuming manual set-ups is eliminated, helping to minimise downtime. The new sensors were installed and commissioned in just four days, compared with the six days that had been allocated for the work. As a bonus, the upgrade also came in under budget. The new level monitoring and control system has operated faultlessly since it was commissioned. It has been welcomed both by the plant operators and the managers at the brewery because it makes their lives much easier. Marston’s is now considering rolling out similar systems to other plants in its group. n Marston’s Brewery has replaced the sight glasses it traditionally used to monitor levels in tanks by modern IO-Link-supporting sensors. The change has resulted in a more reliable, easier-to-use level monitoring system which integrates with the brewery’s control systems. The new pressure sensors have been inserted into the pipes that supply the top pressure to the bright beer tanks

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