LFP Inox: Reliable in the Food Industry

8. February 2017

High demands placed on level measurement in dairies

The Gropper dairy has been a partner of customers and suppliers alike for more than 80 years. The dairy has become the specialist for brands and now supplies almost every national as well as international trading company. The milk processing is a challenge for the sensor technology. Because of this, the company relies on the level sensor LFP from SICK.




The company offers a large product portfolio ranging from desserts to specialty coffees. What’s more, this does not only include brand names – Gropper has also gained experience in co-packing over the decades. Technical capabilities in particular have a major part to play here, as concepts that are relevant to different target groups require the right packaging and, in turn, the right technologies. Besides even performance and environmental demands can only be met with specific Technologies.

Challenges in milk processing

This hasn’t always been easy. One critical point related to the need to continually measure the level in the product containers. Previously, the Gropper dairy had always used a float. However, the weld seams of the float would burst after a certain amount of time. A further disadvantage is that lumpy products can settle in the gap between the float and measuring rod, which is then difficult to clean. Difficulties also arose on the dairy’s second production line, but this time they were of a different kind. A capacitive probe that was in use kept encountering the same temperature problem. During production preparation, the machine has to be sterilized first before production can begin. The highest temperatures of the entire process occur during this thermal process. This high level of strain broke the insulation surrounding the insulated rod, causing a short-circuit. This kind of damage to the probe, or more specifically the resulting failure, is frustrating because, in the worst case, the fault is only noticed when an attempt is made to start up production.




Innovative level sensor from SICK: the LFP

The search for suitable alternatives led to cooperation with SICK AG. SICK was looking for a partner to test the LFP on a new product involved in the level measurement of liquids and bulk materials. Until this point, cooperation between Gropper and SICK had mainly focused on supplying spare parts for laser distance measurement in photoelectric sensors, which were built into the packaging machine.

The requirements of the new sensor system quickly became clear to Gropper: “The head must be as small as possible due to the restricted installation space. This includes the probe head, which contains the evaluation electronics. It must not be influenced by temperature because cleaning the entire filling machine requires high temperatures – and sterilizing it needs to be even higher. And the process connection must be microbiologically immaculate and hygienically clean.”, explains Berthold Burgmeier, Head of Technology at the Gropper dairy.  Reliability, robustness, efficiency, and hygiene were to bring Gropper’s sensors completely up to date.




Excellent performance by the LFP

Almost three years later, five LFP sensors from SICK are now in use at Gropper. Since the two companies began working together and the sensors were installed, the dairy has not experienced any more probe failures. The LFP probe has enabled the temperature difficulties to be completely resolved and otherwise there have been no further problems. The behavior of the foam in the product is no Problem for the level sensor. This, in particular, is one of the LFP probe’s strengths. The LFP series boasts a wide application range and is currently divided into LFP Cubic and LFP Inox. Among other products, it is especially suitable for those that produce a lot of foam, as is the case with dairy products, for example. Because the probe is capable of suppressing foam and therefore of delivering a precise result

The design and material properties of the LFP also mean that using the new level sensor is convenient for Gropper. The LFP should not normally show any signs of wear, as the only object that protrudes into the product is a stainless steel rod. This aspect also has the added advantage of being hygienic. It is not a float guided by a rod, and it is not an insulated rod that has the same problem of the temperature not being consistent. Instead, there is just a stainless steel rod which is incorporated above with a seal.



Progress tailored to sustainable quality

The LFP is particularly suitable for small containers due to the guided, fixed radar probe, which makes use of the technology applied in guided microwave probes.
This technology, along with food process applications, is still in its infancy and has only recently become affordable. This is why capacitive sensors or floats were predominantly used at Gropper, bringing with them the above-mentioned problems. With the LFP, however, Gropper has finally been able to modernize its technology. What’s more, the LFP is not only beneficial from a technical point of view, it is also highly valuable economically speaking – making it an extremely interesting prospect for Gropper. This is not only evident in its long service life, but also in its visible details. The LFP probe rod, for example, can be shortened in length. A standard probe rod of a standard length can therefore be purchased and cut to size on site, making it extremely easy to adapt to the relevant application. This also means that Gropper can reduce the range of spare parts it has to stock in its warehouse. This is not an option for other continuous level measurement technologies – a further advantage of the LFP.




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