Brothers Philip and John Tomlinson founded Tomlinson’s Dairies over 30 years ago in response to demand for fresh bottled milk from their family’s farm. After seven years of running a doorstep delivery service, the Tomlinsons built a dedicated dairy next to the farm in Minera, Wrexham in 1990. In 2012 they moved to a brand new dairy fitted with the latest equipment. Over 70,000 square feet in size and employing 115 staff, it has the capacity to produce in excess of 100 million litres of milk a year. They now supply over 300 outlets across Wales, the Midlands and the North West of England.
The challenge
Minimising product loss is hugely important to the economy of any dairy. Yet when moving to a new automated site in 2012, Tomlinson’s Dairies was faced with the potential loss of thousands of litres of milk during the line flushing process between batches. As engineering manager Stephen Landen explains, “With an automated system you need to be able to distinguish water from milk at each pasteuriser start and finish. If you can’t accurately make that distinction there’s potential wastage every time. On the old site we dealt with the product loss manually to try to save as much milk as possible but we can’t do that with automation and higher process speeds.” When the new site was built efforts were made to reap the maximum benefit from the automated system and minimise product loss.
The solution
Endress+Hauser recommended the OUSAF11 sensor that uses light absorbance to detect product in the water: the more milk present, the less light gets through. Even a low concentration of product in the water will cause a significant signal peak, allowing customers to respond quickly to any loss. “It’s doing a very good job at identifying the water/milk interface,” says Stephen Landen. “As soon as we see that distinct signal we can divert the interface to a dedicated storage tank.” Tomlinson’s is now considering using the sensor technology for a product identification application: distinguishing between different grades of milk. As homogenisation results in uniform distribution of fat in the milk, the sensor can be used to measure that content accurately and with high levels of repeatability, reducing labour-intensive laboratory measurements. As the only sensor in its class to offer glass-free components, there is no danger of contamination within the process. Sensitivity can even be adapted to the demands of the application with a choice of optical path length (5 or 10mm). Tomlinson’s Dairies chose Endress+Hauser to supply the analytical equipment, as well as electromagnetic flowmeters, hydrostatic level transmitters and pressure transmitters for the new site.
The benefits
The company has seen a significant cost-saving since introducing the OUSAF11 sensors for turbidity measurement. As Stephen Landen explains, “We’re probably recovering about 2000 litres of milk a day thanks to this equipment. That works out at a saving of approximately £700 a day, so it’s already a significant saving and we’re not using it to its full potential yet”. As well as meeting all the dairy industry’s hygienic demands, the sensor is virtually maintenance free. “Once it’s set up and commissioned you don’t have to do a lot to it,” agrees Stephen. “I’d definitely recommend it to other dairies. We’ve had visitors come round and look at our automation and they’ve been impressed with how the turbidity sensors operate within our automated process.”
