Premium EHEDG/3-A/ATEX Rotary Lobe Pump: Front-Loading Mechanical Seal OMAC C/CF

A rotary lobe pump is a type of rotary positive displacement pump. Two lobe-shaped rotors rotate in opposite directions, synchronized by a timing gearbox at the rear, maintaining a very small clearance and never making direct contact with each other. As a result, the pump chamber requires no lubrication, generates no metal particles, and does not contaminate the product.

With each revolution, the cavities between the rotors and the pump casing draw fluid in at the inlet and push it to the outlet at a fixed volume. This mechanism produces smooth, low-pulsation flow with low shear on the fluid structure — an important characteristic when pumping cream, sauce, yogurt, fruit-particle liquids, or meat pieces. This also represents a clear difference from centrifugal pumps (which are better suited for thin fluids and generate higher shear).

The main wear components in a rotary lobe pump are the mechanical seal and the rotor clearance. Therefore, the seal design — in particular how it is removed and installed — directly affects maintenance cost and downtime.

These three groups of standards are often mentioned together but address different concerns. Understanding each correctly helps you determine which certifications a pump series needs to meet for each production area.

The OMAC C/CF series is designed to meet all three simultaneously: EHEDG and 3-A for hygiene requirements, and ATEX for areas with explosion risk. This makes it suitable for production lines that process shear-sensitive fluids while also working with volatile solvents or flavorings.

On many rotary lobe pumps, replacing the mechanical seal requires removing the entire pump body from the pipeline, which leads to production line interruption and contamination risk when the pipeline is opened. The OMAC C/CF series uses a front-loading seal: simply open the pump chamber cover to access and replace the seal immediately, while the pump body remains on the pipeline.

For food or pharmaceutical production lines running in batches and performing regular CIP/SIP, the seal is a wear part that requires periodic replacement. The ability to replace it quickly on-site helps reduce downtime and simplifies the cleaning procedure after maintenance. This is a point worth considering when total operating cost depends more on maintenance downtime hours than on the initial purchase price.

When both hygiene and pressure requirements are high, two options worth considering in the OMAC catalog are the C/CF series (focused on certifications and maintenance) and the BF series (focused on surface roughness and full stainless steel construction).

General guidance: choose C/CF when a complete EHEDG/3-A/ATEX certification package is needed and on-site seal maintenance speed is a priority; choose BF when preference is for a smooth product-contact surface (0.8–2 µm), convenient Tri-Clamp connections, and operation at pressures up to 20 bar. Product-contact materials in both series are AISI 316L and both support CIP/SIP.

Advanced rotary lobe pumps deliver value at positions where the fluid is both shear-sensitive and high-viscosity, sometimes containing solid particles, and where the area requires strict hygiene:

• Food & beverage: transferring cream, sauces, jam, pastry filling, fruit-particle liquids; structure preservation and regular CIP/SIP are required.
• Pharmaceuticals: syrup, gel, suspensions in areas requiring hygienic design and material traceability.
• Cosmetics: moisturizing creams, lotions, high-viscosity fluids requiring smooth, low-shear pumping; areas that may contain solvents require ATEX.

For thin fluids at high flow rates, sanitary centrifugal pumps are generally more economical; for very high-viscosity fluids, eccentric screw pumps are an alternative. Rotary lobe pumps occupy the middle range: medium-to-high viscosity, shear-sensitive fluids, potentially containing particles — exactly where the C/CF and BF series perform well.