A hygienic centrifugal pump is a centrifugal pump whose wetted components are designed specifically for the requirements of the food, beverage, pharmaceutical and cosmetics industries. The pumping principle is identical to that of a conventional centrifugal pump, but the construction is specifically engineered for residue-free cleaning and contamination control. High-grade corrosion-resistant stainless steel, electropolished surfaces and a crevice-free design without dead spaces prevent residues from building up anywhere in the pump. A closer look at how these pumps work shows what this means for design and operation in practice.
Hygienic Centrifugal Pumps
Technical Data & Characteristics:
- Delivery rate: up to 300 m³/h (1,320 gal/min)
- Delivery head: up to 120 m (393.7 ft)
- Pressure: up to 63 bar (913.7 psi)
- Viscosities: up to 500 cSt
- Temperatures: -20 °C up to 180 °C (-4 up to 3568 °F)
- Gases: up to 15 %
- Solids: up to 25 % (max. 10 mm)
- pH-value: 0 – 14
- Installations: horizontal, vertical
- Submersibilities: none
- self-priming possible for some models
- Suction hight: max. 7 m (23 ft)
- sealless design possible
- ATEX: Ex Zones 0, 1, 2 and 22
- according ISO or EN standard
- according FDA, 3A Sanitary, EHEDG, GMP
- Drives: electro, hydraulic, compressed air
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As with any centrifugal pump, a rotating impeller performs the actual pumping work. Driven by the pump shaft, it sets the medium in motion and generates centrifugal force. The liquid is forced outwards towards the edge of the impeller and channeled from there through the pump casing to the discharge port. This creates a pressure drop at the inlet, allowing fresh medium to flow in continuously. This basic pumping principle applies equally to standard and hygienic centrifugal pumps.
The difference from a standard centrifugal pump lies not in the pumping principle but in the way it is engineered. To meet hygienic requirements, every component in contact with the medium is designed for residue-free cleaning:
- Impeller: Usually of open or semi-open design, so that no dead spaces are created in which product residues could settle.
- Casing and seals: Casing, impeller and other wetted parts are made from stainless steel and built without crevices, leaving no gaps for deposits or microbial growth.
- Shaft sealing: Typically, a mechanical seal that remains leak-tight and wear-resistant even under frequent CIP operation.
- Connections: Standardized hygienic fittings such as clamp connections or dairy pipe thread couplings. Clamp connections can be opened particularly quickly and without tools, whereas threaded connections generally require tools.
Taken together, this construction ensures that the pump delivers reliably in operation and can be cleaned completely and without residue between production runs, with no need for disassembly. Depending on the pumping task, this basic principle is implemented in different designs.
In principle, a hygienic version is available for almost every type of centrifugal pump, provided the manufacturer offers this variant and it complies with relevant hygienic design standards and requirements, such as those of EHEDG, 3-A Sanitary Standards or the FDA.
Hygienic centrifugal pumps differ in their construction in terms of the number of stages, the installation position and the impeller design. These aspects are determined by the medium being pumped, the required discharge pressure and the space available on site.
- Single-stage or multistage: Single-stage versions cover most standard applications with a single impeller. Multistage versions arrange several impellers in series and therefore achieve greater heads and higher pressures.
- Horizontal or vertical: The installation position depends on the space available on site as well as on the requirements for complete drainage and shaft arrangement.
- Open or semi-open impeller: Open impellers are tolerant of solids in the medium. Semi-open impellers are offered for more demanding applications.
In addition, hygienic centrifugal pumps can be combined with optional equipment, for example a hygienic motor cover to protect against splash water, a lubricated mechanical seal for media prone to crystallisation, a long-coupled version for hot products, or a heating jacket where the medium has to be held at a defined temperature.
Compared with standard centrifugal pumps and alternative pumping technologies, hygienic centrifugal pumps offer a range of advantages that make them the first choice for sensitive processes:
- Reduced contamination risk in daily operation: Because no product residues can settle inside the pump, the risk of microbial growth and cross-contamination between batches is significantly reduced, without requiring additional intervention during normal operation.
- Reduced downtime: Complete drainability allows efficient cleaning by CIP and SIP procedures without disassembly. This shortens the changeover time between two production batches.
- High process reliability: Certification to EHEDG, 3-A Sanitary Standards or FDA requirements provides documented evidence to auditors and customers and ensures that the pump operates reliably in compliance with the required hygiene standards.
- Corrosion resistance: The stainless steel used withstands aggressive cleaning agents such as acids and alkalis, which are applied regularly in CIP operation.
- Efficient operation: Even in a hygienic design, centrifugal pumps run efficiently and smoothly. Well-matched shaft bearings also contribute to low wear.
- Straightforward servicing: The modular construction of many product series allows comparatively quick seal replacement without always having to dismantle the entire pump.
How these advantages translate into practice becomes clear across a wide variety of applications in many different industries.
Wherever liquids have to be pumped under controlled hygienic conditions, hygienic centrifugal pumps are the technology of choice. The following industries and processes are among the typical fields of application:
- Food industry: Hygienic centrifugal pumps are the standard solution for handling flavourings, concentrates, oils, syrup and juices, as well as for process water in food production.
- Beverage industry and breweries: In breweries, hygienic centrifugal pumps transfer mash, wort, must and yeast, and are frequently used for CIP return flow during cleaning. Self-priming versions are particularly suitable here, since gas-laden media occur at certain stages of the brewing process and during yeast propagation. In beverage production more broadly, these pumps are used for soft drinks, beer, wine and spirits.
- Dairy industry: Milk and dairy products place especially high demands on complete drainability and cleanability. Standardized connections such as dairy pipe threads or clamp couplings are common in this sector.
- Pharmaceutical and cosmetics industry: Pumping highly purified water, WFI (Water for Injection), nutrient solutions or active ingredient solutions in pharmaceutical production is subject to the strictest hygiene requirements. Pumps with the relevant certification are also used for alkalis, acids and disinfectants in process engineering, as well as for formulations in cosmetics production, frequently with EHEDG or GMP documentation.
- Water treatment: In processes with high purity requirements for the water, such as ultrafiltration, hygienic centrifugal pumps ensure reliable delivery without affecting the treated medium.
- CIP and SIP cleaning circuits: Hygienic centrifugal pumps are used not only as product pumps but also within the cleaning systems themselves, circulating cleaning and disinfection media through the plant.
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