Sanitary Twin-Screw Pump

In sanitary fluid processing, pump selection involves more than achieving a required flow rate. Product viscosity, pressure differential, temperature, solids content, cleanability, and the ability to maintain stable transfer can all influence pump performance. The SLGP Sanitary Twin-Screw Pump is designed for these demanding conditions, combining positive displacement conveying with non-contact screw operation, reversible flow, wide speed control, and a hygienic internal flow path.

The twin-screw configuration makes the pump suitable for applications where conventional centrifugal pumping may become less effective as viscosity increases or where gentle, continuous product transfer is important. Depending on the selected configuration and operating conditions, the same pump can also participate in CIP and SIP circulation, giving process engineers greater flexibility when designing hygienic fluid systems.

How the Sanitary Twin-Screw Pump Moves Product

The SLGP pump uses two screws rotating inside a precisely designed pump chamber. The screws remain mechanically separated from each other and from the pump casing while creating continuously moving cavities that carry the product from the inlet toward the discharge.

Unlike reciprocating positive displacement pumps, the twin-screw arrangement produces continuous axial conveying rather than repeated suction and discharge strokes. This results in low-pulse transfer and can help reduce unnecessary mechanical stress on the processed product.

The non-contact screw design is also important when handling fluids with limited lubricity or certain corrosive characteristics. Because the primary rotating components do not operate through direct metal-to-metal contact, the pump can be adapted to a wide variety of sanitary process media when the material selection and operating conditions are properly matched.

Wide Operating Range for Different Process Conditions

One of the defining characteristics of the SLGP series is its broad operating range. Depending on the model and screw configuration, the pump can cover applications from relatively low flow rates through high-capacity transfer duties, with the supplied model range extending from approximately 0.5 t/h to 148 t/h under the specified conditions.

The maximum operating speed is model-dependent. Some models in the supplied range operate at up to 2,900 rpm, while the overall SLGP design can reach speeds of up to 3,600 rpm. This wide speed range allows the pump to respond to different product viscosities and process requirements without relying solely on a change of pump size.

The pump is designed for viscosity conditions extending up to 500,000 cSt. However, viscosity capability should always be evaluated together with speed, pressure differential, temperature, suction conditions, and screw selection. A high viscosity rating should not be interpreted as a universal operating point for every model.

Reversible Pumping for Flexible Process Design

The SLGP Sanitary Twin-Screw Pump supports both forward and reverse operation. Changing the direction of shaft rotation reverses the conveying direction, allowing the pump to transfer product in either direction without mechanically reconfiguring the pump.

This capability can simplify process layouts where the same pump is required to serve multiple tanks or transfer paths. It can also be useful for product recovery and selected cleaning operations.

For sanitary processing equipment, this flexibility can reduce the number of dedicated transfer components required in a system while giving engineers more freedom when arranging tanks, pipelines, and process equipment.

Designed for Hygienic Processing and Cleanability

Cleanability is a fundamental consideration in sanitary pump design. Product-contact areas should minimize locations where residual material can remain after production, particularly when the same equipment is used for multiple products or must undergo frequent cleaning cycles.

The SLGP pump uses a hygienic internal flow path designed without conventional dead zones. This supports cleaning and helps maintain the sanitary condition of the product-contact surfaces.

The pump can also be configured with different shaft-sealing arrangements, including single mechanical seals, double mechanical seals, rubber shaft seals, and packing seals. The appropriate sealing configuration depends on the product, operating pressure, temperature, cleaning procedure, and application requirements.

An electropolished finish can also be selected where the process requires an enhanced sanitary surface finish.

One Pump for Product Transfer and CIP/SIP Duties

A particularly useful aspect of the twin-screw design is its ability to operate across substantially different process conditions. When correctly configured, the SLGP pump can be used for both product transfer and cleaning circulation.

During production, the pump handles the process medium according to the required flow, viscosity, pressure, and temperature. During cleaning, the same pump can circulate the cleaning medium through the process loop.

The stated media temperature capability reaches 130°C, while the cleaning temperature can reach 140°C, subject to the selected configuration and operating conditions.

Using one pump for both duties can simplify equipment planning. Instead of automatically installing a separate CIP pump, engineers can evaluate whether the main twin-screw pump can perform the required cleaning circulation. Where appropriate, this approach can reduce equipment count, installation space, and associated piping and valve requirements.

Handling High-Viscosity Products and Particulate Media

Twin-screw positive displacement technology is particularly relevant to products whose flow behavior changes significantly with viscosity.

The SLGP series can be applied to fluids across a broad viscosity range and can accommodate particles up to 40 mm in diameter, depending on the selected pump configuration and actual product characteristics.

This makes the technology relevant to selected food, beverage, pharmaceutical, cosmetic, chemical, and other sanitary processing applications where the product may contain suspended or soft solid particles.

Rather than relying on high-speed centrifugal action, the screws continuously convey the product through the pump chamber. This can provide a more controlled transfer mechanism for products where excessive mechanical treatment should be avoided.

Matching Pump Configuration to the Process

The SLGP series uses a modular approach that allows pump body sizes and screw dimensions to be selected according to the required operating conditions. Different screw configurations can produce different flow characteristics under comparable viscosity, pressure, and speed conditions.

This means pump selection should begin with the actual process rather than simply choosing a model according to nominal flow. Product viscosity, required capacity, discharge pressure, suction conditions, operating temperature, particle characteristics, cleaning method, and desired speed range all need to be considered together.

For example, a product requiring high viscosity handling at relatively low speed may require a different screw configuration from a low-viscosity liquid that needs high-speed transfer. Similarly, an application involving CIP/SIP should consider cleaning temperature, seal construction, and the required circulation conditions during the selection process.

Sanitary Twin-Screw Pump for Complete Processing Systems

The SLGP Sanitary Twin-Screw Pump can be integrated into hygienic production systems where stable product transfer, flexible flow direction, cleanability, and broad operating capability are required.

Its non-contact twin-screw design provides continuous positive displacement conveying, while reversible operation expands system flexibility. Wide speed adjustment allows the pump to respond to changing process requirements, and its hygienic flow-path design supports cleaning-oriented applications.

For food and beverage, pharmaceutical, biotechnology, personal care, and other sanitary industries, the final pump configuration should be selected according to the actual product and process conditions rather than relying on a single nominal specification.