Foodstuff must be multiply conveyed from one station to the next as part of the production process. From a hygienic point of view , transportation in closed systems is advantageous. Therefore, foodstuff pumps are widely used for liquid but also for pasty or not flowing products. An alternative would be conveyor belts but they do not guarantee uninterrupted transportation in containers.
The term foodstuff pump does not stem from the delivery principle, rather more from the application. There is a wide variety of designs. Centrifugal pumps can be utilised for liquid media while positive displacement pumps are utilised for more viscous media. Twin screw pumps can either be utilised as a foodstuff pump for the process as well as a conveying pump for the CIP process.
Regardless of the conveyor data, pressure and flow volume are imperative for all foodstuff pumps so that there are no negative effects on the product quality due to the transportation. This requires initially that there is a hygienic design that prevents that the products are affected by germs during the transportation. The design and construction should be free of cavities and indicate a surface quality finish which easily guarantees safe cleaning.
Usually surface roughness of below 0.8 µm is set as a benchmark for foodstuff pumps. An EHEDG Certification, or a 3A Approval are an indication of a hygienic design. The most common utilised material is 1.4404 (316L). For aggressive media, there are also higher-grade stainless steels such as Duplex or also 1.4539 which can be considered.
Another aspect for foodstuff pumps is the prevention of product exposure to abrasion from the pump. Wearing parts such as the stators from eccentric spiral pumps or scraper gates from sine pumps cause a continued entry of foreign substances into the product so that the suitability of these pump principles should be questioned as a application-dependent utilisation for foodstuff pumps. Finally, it must be ensured that the product characteristics are not affected by the mechanical effects from the conveying procedure in a negative way.
Differentiating functional principles creates considerable differences within the group of foodstuff pumps. Centrifugal and rotary pistons accelerate the product radially, resulting in considerable deflections while operating principles such as, for example, twin screw pumps result in a more uniform conveyance with low accelerations.
The range of application in terms of volume, quantity, pressure, viscosity and temperature has been broadly covered for foodstuff pumps. So it may be that the task is to convey your frozen juice concentrate at temperatures below the freezing point but also to convey liquid sugar masses at 150°C. Some media are water-like while others, for example butter or dough masses, are so viscous that they must be fed through the extruder devices of the pump. All these requirements and boundary conditions must be considered when selecting a suitable foodstuff pump.
The twin screw pump impresses with its flexibility when foodstuff pumps are compared. One and the same pump can convey not only liquid but also highly viscous media by adjusting the rpm. Likewise a wide temperature band can be catered for without structural adjustments.