Level Measurement How Sensors Ensure Precise Filling in Yoghurt Production

Author / Editor: Jürgen Skowaisa* / Dr. Jörg Kempf

The yoghurt producer La Fageda has been proving every day for 25 years that a business run by a team of people including persons with disabilities can be successful. The recipe for this is a mix of solid personal commitment, local raw materials and a clever marketing concept — and a perfectly coordinated sensor technology as an important “ingredient”.

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At La Fageda, Vega sensors control the level to keep the yoghurt filling process running smoothly.
At La Fageda, Vega sensors control the level to keep the yoghurt filling process running smoothly.
(Source: Vega)

The goal: Produce the tastiest yoghurt. But how do you do that? Well, there is a way to do it, and it’s much different from the methods of the big market leaders in the food industry. La Fageda, located in the Garrotxa district, in the region of Catalonia in northeastern Spain, is one of the region’s largest employers. Of the 310 employees, 180 are physically handicapped, mentally ill or mentally disabled. Hardly anyone here can handle eight-hour workdays, yet management provides an appropriate job for everyone.

Since 2009, the company’s turnover has grown by an average of five percent annually. In 2017, it was about 20 million euros. The company, whose product portfolio includes not only yoghurt but also ice cream, jams and desserts, has long since made a name for itself outside Catalonia. International delegations come every day to get informed about the plant. There are now around 40,000 visitors per year. Although La Fageda also benefits from public grants and the cooperation with private companies, these account less than ten percent of total revenue.

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The Unique “Yoghurt from the Farm” Concept

The idea for La Fageda came from the psychologist Cristóbal Colón, who decades ago was looking for meaningful job for the patients of the hospital in which he worked, outside the usual workshops for the disabled. After various — sometimes quite bumpy — attempts, the current La Fageda estate was acquired. Initially, the focus was on the sale of milk. When the quota regulation of the EU was introduced, it was no longer profitable to continue with milk alone. For that reason La Fageda concentrated on yoghurt production. It was clear early on that nobody would buy the yoghurt just out of compassion. So the company focused simply on producing the tastiest yoghurt on the market. The secret is actually quite simple: The yoghurt is produced in the traditional way, without whey powder, thickeners or colourants. The milk is still supplied by the farm’s own cows and five further farms of a cooperative affiliated to the project. The “yoghurt from the farm” concept paid off and is still successful today.

Reliable Supply for Filling

The decisive factor for success was that La Fageda professionalised its production and marketing at an early stage. As a consequence, La Fageda’s production is subject to the same standards of productivity and hygiene that are common in the food industry. Strict requirements are placed especially on the filling equipment, which has to function like clockwork. This is where the yoghurt is fed into the filling machine. Here, the filling level is continuously measured in a small feed container (height approximately 700 – 900 mm, diameter 600 mm) during the filling of the various yoghurt and dessert varieties. A constant level is necessary to ensure that the filling machine does not come to a standstill. Every hour, 12,000 yoghurt cups are filled in the one machine, and another 20,000 in two other machines.

Until recently, there was no continuous level measurement here. The capacitive sensors that were installed for maximum and minimum level detection are now being used as “alarm sensors”. However, the company wanted to optimize the filling process, so it was looking for a continuous measuring system. Ultimately, an engineering company recommended the guided radar sensor Vegaflex 81, which is appreciated in many industries for its reliability and versatility. The big advantage of Vegaflex is its independence from temperature, pressure and vacuum.

There is no build-up that could become a problem for Ve­gaflex 81, because the funnel has a self-cleaning system inside. However, the problem for many measuring principles is the foam that forms as the yoghurt passes through the funnel in the container. A small agitator at the bottom of the yoghurt container can also lead to inaccurate measurements. Vega­flex 81 is particularly non-sensitive to foam and build-up on the probe. That’s why the instrument can cope with this “disturbance” and deliver reliable measuring results, ensuring that the filling system runs smoothly.