BEVERAGES

 

Using infrared technology
to monitoring filling level


High machine speeds put a quick end to visual checks in filling businesses. Random samples can not serve as the level staff for quality management in companies aspiring to be certified in compliance with the 9001 DIN ISO industrial standard.

 


Accordingly, devices for monitoring filling level usually form part of the standard equipment when new units are purchased in a large number of filling businesses in the foods and beverages industries.

Nearly every second filling machine leaving the KRONES factory in Neutraubling is fitted with an IR filling level control system by RETEC GmbH.



The infrared procedure is
environmentally friendly and is not 
subject to approvals or radiation limitations.


Infrared light versus radiation

Measurement technologies based on gamma rays and X-rays and high-frequency technology were among the best-known ones in the past. However, there were drawbacks associated with each of these. 

These included serious points like mandatory labeling for radioactive technologies, special provisions relating to protective equipment and measuring inaccuracies in addition to the fact that significantly more technical work was required to ensure smooth operation.

Infrared systems to monitor filling level were installed in the new filling units at Krones AG in Neutraubling in Germany as early as 1993. Since then, the devices have very reliably satisfied the highly diverse demands made on them throughout the world.



Typical practical duties 

Units designed for operation in wet conditions permit operation of the devices with absolutely mandatory authorization.

A complex sending/receiving procedure with fine resolution enables the object being examined to be checked very precisely. By using compact measuring sensors, a unit can be checked for underfilling or overfilling, whereby the two items can be selected individually.

Everyday filling situations that demonstrate the benefits of infrared technology particularly clearly are described in the following: 

When starting the line up again after brief standstills of the filling unit, high-pressure injection is used to cause certain kinds of beer to foam so that air can escape through the bottle neck.
In this case, the bottles are underfilled intentionally by approx. 10 - 15 mm. The infrared system can identify the differences between the consistencies of foams and liquids much more accurately, to the effect that it can also deal with them better than other methods.

Unfavourable relationships between receptacles and their contents in terms of measurement technology caused by fluctuations of the glass thickness or impurities in the glass do not have any detrimental effect on the measurement accuracy in a direct comparison when using infrared technology.

The infrared filling level monitoring system doesn’t include interfering edges like, for example, metal clips or plastic clips for easy opening of closures in the statistics of the respective filling operation.


Application
The filling level monitoring system is controlled by microprocessors and is well suited for receptacles that are permeable to infrared light and have liquid or pasty contents. 

The system primarily focuses on filling processes in the foods and beverages industry.

Infrared technology also takes account of requirements related to the measurement accuracy demanded in the pharmaceutical industry.

Accordingly, they are used for very diverse bottle shapes and sizes ranging from ampoules for injections to different types of bottles for beverages and all the way to receptacles for baby food. This also illustrates the range of the filling goods.



The measuring principle-
the microprocessor program

The program independently selects the necessary testing tolerances via an automated self-learning mode.

The fact that the system is self-monitoring obviates the necessity of calibrating or readjustment by the operator. 

If an object moves through the infrared sending/receiving unit with no contact, it is triggered internally irrespective of the material (glass/PET). This signal elicits one measurement per 0,5 - 1 mm in the range of the filling level across the entire width of the object, i.e. the object is analyzed spectrometrically in order to determine the exact filling level.

The respective diameter of the object appears as a surface in the evaluation procedure.

The optical refraction causes the light power sent and that actually received to differ. 

Receptacles are evaluated as being well filled, underfilled or overfilled, depending on the evaluation of the surfaces below the measurement curves that are visible when a computer screen is used.

The evaluation programs use various algorithms during this procedure.



On-line Service

The slogan „It’s the information that travels - not the staff“ takes advantage of modern technology.

When remote diagnosis or remote maintenance of the system are carried out, the data is transferred via a standard telephone line and an integrated modem.

Immediate help within seconds without any expensive service deployment brings the experts on-line on site, thereby providing optimum after-sales service.



Conclusion

The process for monitoring filling levels described in the foregoing demonstrates that technologically convincing, future-oriented developments provide a meaningful supplement for new products as well as existing products. Beyond that, they can set new standards in the important field of service.