Sanitary Screw Pump for Food Processing: EHEDG/3A Standards, CIP/SIP Cleaning

The eccentric screw pump (progressive cavity, also called cavity pump) is a single-shaft positive displacement pump. The single-lobe helical rotor rotates eccentrically inside a double-lobe rubber stator, creating sealed cavities (pockets) that move steadily along the pump axis. This mechanism produces a stable flow rate directly proportional to rotational speed, with virtually no pressure pulsation.

For food applications, the key attribute is low shear force. The fluid travels within sealed cavities rather than being battered by high-speed impellers as in a centrifugal pump, so product structure is preserved: jam pieces remain intact, sauce emulsions do not separate, and minced meat fibres are not torn apart. The pump also handles high-viscosity fluids and fluids containing solid particles or fibres effectively, with the ability to self-prime and reverse direction for back-suction when needed.

In food and beverage plants, product-contact equipment must meet hygienic standards to ensure safety. EHEDG (European Hygienic Engineering & Design Group) and 3-A Sanitary Standards are two widely adopted sets of design criteria aimed at eliminating dead zones, crevices, and rough surfaces — areas where microorganisms accumulate easily and are difficult to clean.

Sanitary-design pumps feature smooth product-contact surfaces, food-grade stainless steel materials, appropriate seals, and a construction that allows easy disassembly. More importantly, this design is compatible with CIP (Cleaning In Place) and SIP (Sterilization In Place) processes, enabling cleaning solutions and sterilizing steam to reach all internal surfaces without removing the pump from the production line.

Nova Rotors (Italy) offers several eccentric screw pump ranges for the food industry. The Diamond DX-JX series features sanitary design meeting EHEDG/3A standards with CIP/SIP compatibility — suitable for pumping shear-sensitive fluids requiring structural preservation and high hygienic safety. Also available is the HE hopper-style range with trolley for food and wine applications.

For fluids with very high viscosity, the sanitary twin-screw pump range handles products at very high viscosity levels with corresponding pressure ratings depending on configuration. When precise sanitary metering is needed for cream, sauces, gel, or honey, the DM metering range delivers a flow rate proportional to speed, ideal for filling and blending operations.

The rotor–stator pair is the contact surface and wears over time. The critical rule is to NEVER allow the pump to run dry: without lubricating fluid, friction between the rotor and stator generates heat and burns the rubber stator. Therefore, a level sensor or dry-run protection device should be installed for applications prone to fluid depletion.

The rubber stator material (NBR, EPDM, Viton) is selected according to the fluid type and operating temperature; for CIP/SIP applications, resistance to cleaning chemicals and hot steam must be considered. The stator and rotor are scheduled replacement items — having spare parts ready reduces downtime. Thanks to their easy-disassembly construction, sanitary-range pumps allow rapid inspection and cleaning between production batches.