Statistics tell us that every German citizen eats around 9.5 kg of chocolate a year, in the form of bars, hollow figures, pralines and such like. There is a particularly steep rise in consumption at Easter and Christmas. The sweet may be very popular, but it is extremely complicated to make. In particular, the temperature has to be precisely controlled at all times to achieve the later melt-in-your-mouth effect. To avoid there being any gap in the processing chain here, NETZSCH Pumpen & Systeme GmbH has developed a special tempering positive displacement pump. It is designed to meet the strictest hygiene requirements and is also easy to clean. “Chocolate pump” at NETZSCH means a special designed progressing cavity pump. Because of a really wide range of tasks in chocolate production there is also a rotary lobe pump with simi-lar features in a compact full-metal design, the T.Sano®.
The secret of high-quality chocolate is ensuring that the fat crystals contained are configured in the best possible way. This is directly dependent on tempering. If the temperature is too high or too low, chocolate will no longer melt in your mouth or will not have an attractive, shiny finish, but a milky, lacklustre look instead. The viscosity also changes along with the crystal content, and this may lead to problems further on in processing or when filling. Tempering is therefore crucial in terms of quality: Good chocolate needs smooth conveyance at a constant temperature.
An adjustable heating jacket has been added to the NEMO® progressing cavity pump for tempering. This encloses the whole length of the pump, from the mechanical seals to the pressure ports. It allows the required heat to be kept constant through the various stages of the process. As an option, the complete heating module can also be split into several sections which are controlled separately and can generate different temperatures. This means it is possible for instance to ensure a permanent supply of heat to the mechanical seals, where the fats otherwise often cool down and crystallise.
In order to meet high hygiene requirements in the food industry, the pump has been fitted with open pin joints. These are constantly flushed by the medium which inhibits the deposit of product residues. All wetted surfaces have also been given a polished finish and highly-hygienic mechani-cal seals with no dead spaces have been fitted. The materials used, especially the elastomers, are approved by the FDA and the pumps meet the requirements of the Federal Institute for Risk As-sessment (BfR), along with those of the Russian GOST-R.
The TORNADO® rotary lobe pump was equipped with appropriate features to fulfil the same re-quirements for product protection, residue-free conveying and hygiene.
The model T.Sano with smooth design is a hygienic rotary lobe pump. Its function is based on two rotary lobes in counter-rotation. This moves the medium gently, but continuously from the intake to the discharge side. For the conveyance of chocolate excluding pressure fluctuations or shear forces is fundamental. Additionally, the specially designed internal geometry of the delivery chamber keeps any pulsation at a very low level, ensuring a gentle, continuous product flow. To guarantee the flow of the chocolate it is possible to add a heated lid.
The pump is particularly suitable for use in chocolate and confectionery production due to the material selection. All components used in the T.Sano® rotary lobe pump that come into contact with the medium are made of stainless steel to comply with food safety guidelines. The special oil-free drive of this pump type also helps to protect products and consumers. A toothed belt trans-fers the torque from the motor to the rotary lobes while synchronising their rotation. The motor runs completely without oil, which excludes product contamination. This drive type also makes the pump very compact. The motor is flanged on above the delivery chamber to save space. This also results in a relatively low weight and extremely small installation depth which makes it possi-ble to install the unit into tight spaces. In addition, the cooling ribs in the area of the pump bearing were removed from this type of rotary lobe pump in 2017. Instead, it now has a completely smooth housing to which virtually no dust or dirt can adhere. As a result the pumps are not only EHEDG certified they are also certified with the American 3-A-Certificate.