Elegant solution for hygienic pumping of difficult media

Many products in the food processing and beverage industries require particularly hygienic and safe pumping. Think of baby food, ketchup or syrup. In order to offer better, more customized solutions for these complex tasks, global pump expert NETZSCH Pumps & Systems is expanding its portfolio of hygienic pumps with a new model.

The NOTOS® 2NSH screw spindle pump, with flow rates of up to 200 m³/h and delivery pressures of up to 16 bar, moves media contactlessly between the inner wall of the pump housing and the screws and between the two screws to ensure uniform product flow. Because the pump is made entirely of stainless steel and the screws do not touch, it poses no risk of contamination. Moreover, the pump can be efficiently cleaned (CIP) and sterilized (SIP).

Pumping large volumes

The new hygiene pump is based on the twin-screw 2NS model from the proven NETZSCH NOTOS® screw spindle pump series. The special feature of these pumps is that they can pump large volumes while managing pressures up to 16 bar with a small footprint. "During pump operation, the two interlocking, counter-rotating screws form chambers in conjunction with the pump housing," explains Joaquim de Matos, manager of NETZSCH subsidiaries in the Benelux region. "In these chambers, the medium is moved in a continuous axial movement from the pump inlet to the discharge side." The conventional variant of the NOTOS® 2NSH can further be equipped with a heating jacket and used for vessel emptying. Thanks to the heating jacket, the medium can be pumped at a constant temperature.

Soft, non-contact operation

For safe operation with difficult media, the NOTOS® hygienic pump is equipped with stainless steel screws with a high-efficiency profile that enables high flow rates with low fluid shear. The screws are available with different pitch options, all of which are precisely balanced and offer high efficiency. The stainless steel shafts are designed for high torque levels and can rotate in either direction. "Contamination is not possible here because the screws do not touch each other," Matos said. "For the same reason, dry running is not a problem with this type of pump. Provided, at least, that the mechanical shaft seals are configured correctly. This pump type is therefore ideal for systems with an increased risk of dry-running. Indeed, the unit will not cause or experience any damage in that case."

FSIP® version for easy maintenance

The pump is also available in FSIP® version (Full Service In Place). "FSIP" is a design concept already implemented in numerous NETZSCH products in order to simplify maintenance tasks for service personnel. For the 2NSH, this means that the screws and mechanical seal can be completely installed and removed without removing the pump from the production line. This can significantly reduce downtime for maintenance and therefore offers a high level of convenience and reliability in the processes involved." More specifically, the FSIP® version of the NOTOS® 2NSH features a special pump housing, which allows for quick and easy removal of the pump without separating the unit from the line. The screws can also be replaced without removing the bearings. Different screws of the same size with different pitch are available. The shaft is sealed with low-maintenance mechanical cartridge seals.

Simplified cleaning process

With hygienic and demanding applications in mind, the design of the NOTOS® is focused on an ideal cleaning procedure. For example, the unit has no dead space internally and all surfaces in contact with the medium are mechanically polished to an Ra value of < 0.8 µm. This enables efficient cleaning of the 2NSH. A simplified CIP process also offers additional benefits. "The 2NSH does not require an additional cleaning pump," de Matos said. "In fact, during cleaning, the flow rate of this hygiene pump can be significantly increased. The cleaning solutions thus pass through the pump and downstream system components at the required high flow rate."