Lobe Pumps: Hygienic Rotary Pumps for Gentle Handling

How a Lobe Pump Works

Two rotors sit side by side in the pump head, each driven by its own shaft. Timing gears in a separate gearbox keep them in step, so the lobes never touch each other or the casing.

As the rotors turn:

1. The lobes separate at the inlet, creating space that draws liquid in.
2. The liquid is trapped between each lobe and the casing.
3. It travels around the outside of the casing, not through the middle.
4. The lobes mesh at the outlet and push the liquid out.

Nothing touches inside the pump head, so the product is not crushed or smeared. Flow follows speed closely, and most lobe pumps run happily in either direction.

Choosing the Rotor

Tri Lobe Rotors

This is the most common shape. Three lobes on each rotor give smooth flow and good efficiency on general food, beverage and chemical duties.

Bi Wing Rotors

Two wide wings leave large open pockets, so big pieces of fruit, meat or vegetables pass through whole. They pulse a little more than tri lobe rotors.

Multi Lobe Rotors

Four or more lobes give the lowest pulsation. They suit filling lines, metering and shear sensitive products such as cream.

Most rotors are stainless steel. Rubber-coated or non galling alloy rotors suit products that lubricate poorly or need tight clearances.

Seals for Sticky and Sweet Products

Sugary or sticky products can dry on the seal faces and tear them apart on the next start. The right seal choice fixes this:

• Single mechanical seals: most general and hygienic duties.
• Flushed or quenched seals: water flows behind the seal to wash away sugar, syrup or any product that crystallises.
• Double mechanical seals: hazardous, abrasive or very sticky products, with a barrier fluid between the seals.

Running Tips That Protect the Pump

• Fit a relief valve or pressure switch. A lobe pump is a positive displacement pump, so it will keep building pressure if the outlet is blocked.
• Run thick products slowly. A variable speed drive lets you match the speed to the product and protects delicate pieces.
• Allow for heat. Hot products expand the rotors, so pumps for hot duties need rotors cut with extra clearance. Tell us the full temperature range.
• Never run the pump dry for long. The seals rely on the product or the flush to stay cool.
• Check the timing gear oil at each service. Worn gears let the lobes touch.

Signs Your Lobe Pump Needs Attention

• Falling flow at the same speed, a sign of worn rotors or casing
• Product leaking at the seal or the flush outlet
• Knocking from the pump head, which may mean worn timing gears or bearings
• Oil leaks at the gearbox
• Scoring marks on the rotors or casing