Look behind the scenes
As popular as bakery products are, their production is often not without unforeseen difficulties, as for instance in a company making confectionery products in Southern Germany.
The intention of the company is to convey a pastry mixture with a high proportion of egg white and sugar from the receiver tank and precisely dose it into moulds. However, the infeed of the mixes, whose specific weight is considerably below that of water, cannot be guaranteed. In addition, the medium has a somewhat abrasive effect due to the sugar crystals it contains and this puts additional stress on the conveying system – quite apart from the high demands in terms of hygiene and food safety.
In order to cover this range of requirements, the company decided on a NEMO® hygienic pump. Thanks to progressing cavity technology, these pumps, depending on their size, are capable of dosing to an accuracy of between five and three percent, irrespective of the consistency of the medium, with smaller dispensers even achieving a volumetric accuracy of one percent. This is made possible by the geometrical rotor-stator pairing which produces conveying chambers keeping the same shape during rotation. The same quantity of medium is reproducibly transported in these chambers, which means the volume can be continuously adjusted via the speed. In this way the company can now precisely dose between 450 and 3,500 litres per hour of baking mix into the baking moulds at 1 bar.
Due to the difficult medium, power transmission between drive and rotor in the hygienic pump is achieved via a flexible rod. Whereas open joints would be quickly worn by abrasion and closed joints filled with oil are not permitted with food safety in mind, the flexible rod is heat-shrunk with the connection points to form a hermetic seal at both ends and functions without moving parts, friction surfaces and lubrication. This means high operational reliability and a long service life are achieved with low maintenance costs.
The fact that the pump does not need to be dismantled for cleaning also contributes to this. The streamlined geometry of the conveying area with no dead spaces allows direct cleaning in place. This involves the bakery company using hot water at 60°C to flush the pump for 20 minutes at 400 rpm. The special design and the materials used – above all stainless steel and highly robust elastomers – mean the lobe rotors do not get damaged in the process.