Sanitary Twin-Screw Pump for Surfactants and Detergents: Eliminating Foaming and Phase Separation

Surfactant and detergent formulations can change significantly during pumping. A liquid that appears uniform inside a mixing vessel may develop excessive foam, incorporate air, or show changes in apparent consistency after transfer. For manufacturers, these changes are not simply pumping problems. They can influence the appearance, filling behavior, concentration consistency, and final quality of the chemical product.

This makes the transfer stage an important part of surfactant and detergent processing. The pump must move the formulation at the required rate while limiting unnecessary air incorporation and avoiding operating conditions that disturb the product.

A sanitary twin-screw pump provides a positive-displacement conveying method for these applications. Its continuous screw movement, non-contact operation, adjustable speed, and ability to handle a wide viscosity range make it suitable for controlled transfer of selected surfactant and detergent formulations.

Why Surfactants Behave Differently During Pumping

The defining characteristic of a surfactant is its ability to reduce surface tension and interact strongly with interfaces. This property is essential to detergents, cleaners, emulsifiers, wetting agents, and many other chemical formulations, but it also makes the product more susceptible to foaming when air becomes dispersed in the liquid.

Air can be introduced when the product passes through turbulent regions, when the liquid level is low, or when the pumping conditions create excessive agitation. Once air enters a surfactant-rich liquid, the bubbles may remain stable instead of separating rapidly.

The result can be a product that appears much more voluminous than its actual liquid content. Persistent foam may also make downstream filling less consistent and complicate visual inspection of the finished formulation.

For this reason, controlling the way the product is conveyed can be as important as controlling the formulation itself.

Continuous Conveying Helps Avoid Unnecessary Flow Fluctuation

The SLGP twin-screw pump transports product through continuously moving cavities created by two rotating screws. Unlike reciprocating pumps, the conveying action does not rely on repeated suction and discharge strokes.

This produces a low-pulse transfer pattern, which can be beneficial when a detergent or surfactant formulation needs to move at a relatively stable rate.

The screws also operate without direct contact with each other or the pump casing. The product is conveyed through the space formed by the rotating screw geometry rather than being transferred through repeated mechanical impact.

For formulations in which excessive mechanical treatment is undesirable, this provides a useful starting point for controlling the transfer process.

It is important to distinguish this from claiming that twin-screw pumping automatically eliminates foam. Foam formation depends on formulation chemistry and operating conditions. The pump contributes by providing a controllable conveying mechanism that can be operated without unnecessarily aggressive conditions.

Pump Speed Is a Product-Quality Variable

For surfactants and detergents, pump speed should not be treated purely as a capacity setting.

Increasing rotational speed can increase throughput, but it also changes the way the formulation experiences the pumping process. The appropriate speed therefore depends on the product's viscosity, temperature, required flow, pressure differential, and sensitivity to air incorporation.

The SLGP series has a broad adjustable speed range, with the overall design capable of reaching up to 3,600 rpm. This does not mean that high speed is appropriate for every formulation. Instead, the available range allows manufacturers to identify an operating point appropriate to the particular chemical product.

A lower or moderate operating speed may be preferable when the objective is controlled transfer rather than maximum throughput, while different conditions may be appropriate for more fluid formulations.

The important point is to match pump speed to product behavior, not simply to the maximum capability of the pump.

Viscosity Changes Can Alter the Transfer Behavior

Surfactant and detergent products are available in many formulations, from relatively thin cleaning solutions to concentrated, highly viscous products.

Viscosity can also change during processing. Concentration, temperature, dissolved ingredients, and formulation structure can all influence resistance to flow.

The SLGP pump is designed for a wide viscosity range, with the supplied product information specifying capability up to 500,000 cSt under applicable conditions.

This broad range is useful when different chemical formulations are processed using the same pumping technology. However, the appropriate pump model and operating point still depend on the actual viscosity and process conditions.

For a concentrated detergent, for example, simply increasing pump speed may not be the most effective response to higher viscosity. Product temperature, screw configuration, pressure requirement, and suction conditions need to be considered together.

Temperature Can Change Both Viscosity and Product Behavior

Temperature is another important variable in surfactant and detergent processing.

A formulation may become easier to transfer as viscosity decreases with increasing temperature, but temperature changes can also influence solubility, phase behavior, ingredient compatibility, and the physical appearance of the final product.

The SLGP pump can handle media temperatures up to 130°C under the stated conditions, while the specified cleaning temperature can reach 140°C.

These are equipment capabilities rather than recommended product-processing temperatures. The actual operating temperature should be determined by the chemical formulation and its processing requirements.

For temperature-sensitive formulations, the goal is to maintain a sufficiently stable product condition throughout pumping so that changes in viscosity do not create inconsistent transfer behavior.

Phase Separation Is Primarily a Formulation Issue

Phase separation requires particular care because it cannot be solved simply by changing the pump.

Detergents and surfactant-based products may contain multiple ingredients that need to remain uniformly distributed. Separation can result from formulation incompatibility, concentration changes, temperature variation, insufficient mixing, storage conditions, or other chemical and physical factors.

The pump's role is to transfer the formulation without unnecessarily disturbing its established state.

A twin-screw pump provides continuous displacement and adjustable conveying conditions, allowing the transfer rate to be controlled according to the product's characteristics.

If a formulation has already achieved the required uniformity in the preparation stage, maintaining appropriate transfer conditions can help avoid introducing an additional source of instability.

This is a fundamentally different consideration from using a pump to homogenize a formulation. The twin-screw pump should be viewed as a controlled transfer device, not as a substitute for formulation or mixing equipment.

Handling High-Viscosity Detergent Concentrates

Some detergent products are manufactured as concentrated formulations that are significantly more viscous than their final diluted products.

This creates a different pumping requirement during production. The pump needs to generate sufficient conveying force while maintaining stable product movement through the pump and downstream process.

The SLGP's positive-displacement operating principle makes it suitable for selected high-viscosity formulations. Its operating range can be adjusted according to the actual product condition rather than requiring the process to operate at one fixed speed.

The pump can also handle media containing particles up to 40 mm in diameter under suitable conditions. For chemical products, actual particle characteristics remain important, particularly when particles are hard, abrasive, irregular, or present at high concentrations.

Reversible Conveying for Product Handling

Surfactant and detergent production may involve products with different viscosities or formulations that need to be recovered after transfer.

The SLGP pump supports reversible operation by changing the direction of shaft rotation. This changes the direction of product conveying without requiring mechanical modification of the pump.

For chemical products, this can be useful when a formulation needs to be moved back toward a previous process stage or when residual product needs to be recovered from a transfer section.

The benefit here is primarily process flexibility at the product-transfer level, rather than complete system integration.

Seal Selection for Chemical Formulations

The shaft seal is another important consideration when pumping chemical products.

The SLGP can be configured with single mechanical seals, double mechanical seals, rubber shaft seals, or packing seals. The appropriate option depends on the chemical composition, temperature, pressure, cleaning conditions, and compatibility requirements of the formulation.

For aggressive surfactant concentrates or detergent chemicals, seal compatibility should be assessed together with all product-contact materials. Chemical resistance cannot be determined from the pump body alone.

This is especially important when a manufacturer processes multiple formulations with different chemical compositions on the same equipment.

From Surfactant Concentrate to Finished Detergent

The behavior of a detergent during pumping can change as its formulation develops.

Raw materials may first be dispersed or dissolved, followed by the addition of surfactants, builders, solvents, fragrances, active ingredients, or other components. As concentration and composition change, so can viscosity and sensitivity to air.

At each stage, the pump should be operated according to the actual product condition.

A formulation that is easy to transfer at an early stage may become substantially more viscous after concentration increases. Conversely, a diluted finished detergent may require a completely different operating point.

This is why a broad pump operating range can be valuable: the pumping process can be adjusted as the chemical product changes rather than treating every formulation stage as the same fluid-handling task.

A Controlled Pumping Approach for Surfactant-Based Products

Foaming and phase instability in surfactant and detergent production are closely connected to formulation chemistry and processing conditions. Pump selection cannot independently eliminate these phenomena, but it can influence how the product experiences the transfer stage.

The sanitary twin-screw pump provides continuous positive-displacement conveying, low-pulse flow, non-contact screw operation, reversible transfer, and a wide operating range. These characteristics allow manufacturers to adjust pumping conditions according to viscosity, temperature, formulation stage, and required production rate.

For surfactants and detergents, the objective is therefore not simply to pump faster. It is to establish a controlled transfer condition that respects the physical behavior of the chemical product—from concentrated formulation to finished product—while minimizing unnecessary air incorporation and mechanical disturbance.