How Temperature Affects Hygienic Pump Performance

Temperature is an important consideration in hygienic pumping applications because it can change both product characteristics and operating conditions.

In food, beverage, dairy, pharmaceutical, and personal care processing, a pump may handle product at one temperature and significantly hotter fluids during Clean-in-Place (CIP). These temperature changes can influence viscosity, suction conditions, internal clearances, seals, and elastomers.

Understanding these effects helps ensure the pump is properly selected for the full range of process conditions.

Temperature Changes Viscosity

For many products, viscosity decreases as temperature increases. A syrup, oil, concentrate, cream, or other viscous product may therefore behave very differently at 40°F than it does at 140°F.

Viscosity can affect friction loss through the piping system, pump efficiency, required torque and horsepower, and the type of pump best suited for the application.

For this reason, pump selection should consider the product’s viscosity at its actual pumping temperature. When a process experiences a wide temperature range, viscosity should be evaluated at the relevant minimum and maximum operating temperatures.

Higher Temperatures Can Affect NPSH

Temperature can also have a significant effect on the suction conditions of a centrifugal pump.

As liquid temperature increases, its vapor pressure increases. This reduces the margin between Net Positive Suction Head Available (NPSHa) from the system and Net Positive Suction Head Required (NPSHr) by the pump.

If sufficient NPSH is not available, the liquid can begin to vaporize as it enters the pump, potentially resulting in cavitation and reduced pump performance.

Applications involving hot products or elevated-temperature fluids should therefore account for liquid temperature along with tank level, pump placement, suction piping, pipe diameter, and restrictions when evaluating NPSH.

Temperature Can Affect Internal Clearances

Temperature changes can also affect the internal clearances of positive displacement pumps as components expand and contract. This is particularly important when there is a significant temperature difference between production and CIP.

Applications with large temperature swings may require clearances specifically selected for those conditions. For a more detailed explanation, see our article on Hot Clearance Rotors and Temperature Differentials.

Consider Seals and Elastomers

Mechanical seals, O-rings, and other elastomers must be compatible with the complete process, not just the product being pumped.

During cleaning, these components may be exposed to elevated temperatures as well as caustic solutions, acids, sanitizers, and other chemicals. The combination of temperature, chemical concentration, and exposure time can influence material performance and service life.

Seal and elastomer selection should therefore consider both production and cleaning conditions.

Don’t Overlook CIP Conditions

Normal production conditions are only part of the application. During CIP, the pump may encounter different temperatures, viscosities, flow rates, pressures, and suction conditions than it experiences while pumping product.

For example, a pump selected to move a viscous product at a relatively low speed may also be expected to move low-viscosity cleaning solution at a much higher flow rate. Those two operating points can place very different demands on the pump and system.

Evaluating both production and CIP conditions helps ensure the pump can perform effectively throughout the complete process cycle.

Look at the Complete Operating Range

Temperature should not be considered as an isolated value on an application data sheet. Its effects can extend throughout the pumping system by changing product viscosity, vapor pressure, suction conditions, component clearances, and material requirements.

When evaluating a hygienic pump application, consider the minimum and maximum product temperatures, viscosity at those temperatures, CIP temperature and flow requirements, suction conditions, required flow and pressure, and cleaning chemistry.

Understanding the complete operating range helps ensure the pump is properly configured for reliable performance during both production and cleaning.

For applications involving significant temperature changes, hot products, or demanding CIP conditions, Fristam application engineers and authorized distributors can help evaluate your process and determine the appropriate hygienic pump configuration.