Rotary lobe pumps for dairy, cosmetics and pharmaceuticals: which OMAC series to choose?

The rotary lobe pump belongs to the rotary positive displacement pump group. Two lobe-shaped rotors are driven through a synchronous gearbox to rotate in opposite directions while always maintaining a small clearance rather than contacting each other. With each rotation, the cavities between the rotors and pump casing draw fluid in at the inlet and discharge it steadily at the outlet. Because the rotors do not touch each other, the pump chamber experiences no wear and no lubricating oil enters the fluid.

These characteristics suit the dairy, cosmetics, and pharmaceutical industries well, where fluids are typically shear-sensitive and high cleanliness is required. The pump runs smoothly with low pulsation flow and low shear, preserving the structure of products such as yogurt, fresh cream, sauces, cosmetic emulsions, or pharmaceutical suspensions. Compared to centrifugal pumps, which are suited for thin fluids, lobe pumps handle high-viscosity fluids with solid particles effectively; compared to eccentric screw pumps used for very high-viscosity fluids, lobe pumps are more compact and easier to clean for sanitary production lines.

Dairy and food production lines require pumps that are gentle on the fluid and easy to clean between batches. The OMAC series B is an AISI 316L rotary lobe pump mounted on a cast-iron gearbox, available in 17 sizes from B100 to B680, with flow rates up to 315 m³/h and pressure up to 20 bar. The rotors are available in tri-lobe, bi-lobe, or ACTEON configurations, combined with multiple mechanical seal options to suit various fluids such as fresh milk, cream, soft cheese, or sauces.

When stricter hygiene is required, the BA-BB series upgrades the certification level and cleaning design: BA holds 3-A certification, while BB complies with 3-A Std 02-10. Both feature a self-draining design that allows fluid to fully drain when the pump stops, use 7KFO seals, and support CIP/SIP for convenient in-place washing and sterilization. This configuration is suitable for dairy plants, fermented products, and foods requiring tight microbiological control.

Cosmetic products such as moisturizers, gels, lotions, and emulsions typically have high viscosity and are very sensitive to shear; aggressive pumping can easily cause phase separation or alter their texture. The rotary lobe pump handles this well thanks to its smooth operation and low shear, while also providing metering capability during filling and reversible operation when fluid recirculation is needed.

For cosmetics, series B is commonly selected for its wide size range and variety of rotor configurations, accommodating fluids from thin to thick. When thorough cleaning is needed between product lines of different colors or fragrances, the self-draining design and CIP/SIP of the BA-BB series help reduce cleaning time and the risk of batch cross-contamination. AISI 316L material combined with non-contacting rotors helps maintain product purity and minimizes metal particle generation in the product.

The pharmaceutical industry places high demands on surface cleanliness, sterilization capability, and sometimes explosion protection as well. The OMAC C-CF series is a high-specification configuration certified to EHEDG, 3-A, and ATEX, using front-pull-out seals for quick replacement in place without disassembling the entire pump, helping to reduce downtime and simplify maintenance in controlled environments.

When smooth product-contact surfaces and quick-disconnect connections are needed, the BF series is a full stainless steel option with Tri-Clamp connections, surface roughness of approximately 0.8 to 2 µm, and pressure up to 20 bar. The low surface roughness limits fluid adhesion and makes cleaning easier, suitable for pharmaceutical suspensions, syrups, or semi-finished products where cross-contamination control is critical.

When selecting a sanitary lobe pump, start from the industry hygiene requirements, then move to fluid characteristics (viscosity, solid particles, shear sensitivity), and finally installation conditions. For dairy and food requiring 3-A standards, series B or BA-BB is a reasonable starting point. For high-viscosity cosmetics, series B offers a flexible range of sizes and rotor configurations. For high-standard pharmaceuticals or environments with explosion risk, series C-CF; and when smooth surfaces and quick disassembly are priorities, series BF.

For a compact, low-cost solution for applications with lighter hygiene requirements, the BE monobloc series with IEC flange mounting and bi-lobe rotors is available in 7 sizes from BE110 to BE450, with pressure up to 7 bar and the ability to handle solid particles of approximately 10 to 19 mm. The main wearing parts of a lobe pump are the mechanical seals and rotor clearances, so during operation it is important to control NPSH and select seal materials appropriate for the fluid to extend service life.