IO-Link sensors keep brewery on the level


When Marston’s Brewery needed help to devise a better and more dependable level control solution, it approached sensing experts, ifm electronic. MEPCA found out more. 

Marston’s Brewery is a company with a long and proud tradition – it has been producing its popular and highly regarded English ales at its site in Burton on Trent in Staffordshire since 1898. But although tradition has much to recommend it when it comes to the techniques of beer production, this is not always the case with process control. Modern options can sometimes 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, each of which can hold up to 21,000 litres of beer.

Prior to the update, the plant operators monitored and controlled the level of beer in the tanks manually with the aid of sight glasses – essentially the same system that had been in use since the brewery first opened. The sight glasses required regular cleaning, however, which was a difficult and inconvenient operation, and some were not readily visible, making it hard for the operators to keep track of the levels. As a result, a tank was sometimes allowed to become completely empty, allowing air into the system, which disrupted the operation of the bottling lines.

Key requirements of a new solution were that it should enable accurate automatic control of levels in the tanks, that it should interface with the plant’s existing PLC and SCADA systems to allow the levels to be monitored remotely, and that it should provide clear level indication adjacent to the tanks via digital displays.

After carefully assessing the requirements and noting the need for the solution to be compatible with the hygienic requirements of the food and beverage industry, engineers from ifm electronic proposed that each tank should be fitted with two flush-fitting hygienic PI2796 pressure sensors with integral displays and one LMT100 hygienic level sensor. These sensors incorporate IO-Link interfaces, meaning that digital process values are transmitted, which greatly simplifies interfacing them with the existing plant systems and also ensures that the data they capture will always be transmitted accurately.

The plant systems use an Ethernet network with redundant ring topology to ensure high reliability. The ifm IO-Link sensors were connected to this via AL1121 Ethernet interface modules which, with an IP65 rating, are suitable for installation in the field without additional protection. The requirement for local display of the tank levels was met with E30391 IO-Link display modules, which also connect directly to an IO-Link master port on the AL1121 and, like the Ethernet interface modules, require no additional protection when mounted in the field.

In most applications, the sensors would have been installed on top of the tanks, but in this case, space above the tanks was limited, and access was difficult. The decision was therefore taken to mount the sensors in the pipes that supply the top pressure to the tanks. In this location, the sensors provide identical data, but installation was much faster, easier and safer as no scaffolding was needed.

Despite the exceptionally high reliability of modern sensors, the engineering team at Marston’s wanted to be sure that, should it ever prove necessary, they would be easy to replace. This requirement was satisfied not only by installing the sensors at a convenient working height, but also by an intrinsic feature of the IO-Link system which allows configuration data to be directly loaded into the sensors.

If a sensor needs to be replaced, all that is necessary is to send the configuration data to the replacement via its normal IO-Link connection, and it is then ready for immediate use. The need for inconvenient and time-consuming manual setting up is completely eliminated, which helps to ensure that plant downtime is kept to a minimum.


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