Bi-Lobe
- Indicative Solids Passage
- Up to ~70 mm for soft or compressible solids, depending on model. Hard particles require a separate review.
- Discharge Pulsation
- High
Choose the geometry around the fluid
Rotary Lobe Pump Rotor Profiles
Compare bi-lobe, straight tri-lobe, and helical tri-lobe rotors by solids passage and flow behavior. Choose the profile around the duty, then match the material, speed, and pump size.
1. Bi-Lobe — Larger Transfer Pockets
Two lobes leave larger transfer pockets between the rotor and casing. This favors the passage of large, soft or compressible solids.
- Selection priority
- Soft-solids passage rather than the smoothest discharge.
- Typical duties
- Thick sludge, organic waste, and transfer with soft solid chunks.
- Confirm for the duty
- Check particle size, shape, hardness, and concentration, together with acceptable line pulsation.
2. Straight Tri-Lobe — Balanced Transfer
Three straight lobes divide the transfer into smaller pockets. Compared with bi-lobe, this balances solids handling with lower discharge pulsation.
- Selection priority
- A balance of solids passage and discharge smoothness.
- Typical duties
- Wastewater, municipal sludge, oil transfer, and mixed industrial fluids.
- Confirm for the duty
- Review the actual solids and required flow before selecting the model and operating speed.
3. Helical Tri-Lobe — Pulsation-Free Transfer
Three lobes with an axial twist engage progressively along the rotor length, smoothing displacement for Pulsation-Free transfer.
- Selection priority
- Smooth flow for filling, dosing, and shear-sensitive transfer with small or no solids.
- Typical duties
- Polymer dosing, filling lines, cosmetics, and other product-sensitive fluids.
- Confirm for the duty
- Match speed and viscosity to the product; dosing duties also need delivered-flow calibration.
4. Compare Passage & Pulsation
These passage figures are indicative and model-dependent. Distinguish soft or compressible solids from hard particles; diameter alone does not establish whether a solid can pass.
| Rotor Profile | Indicative Solids Passage | Discharge Pulsation |
|---|---|---|
| Bi-Lobe | Up to ~70 mm for soft or compressible solids, depending on model. Hard particles require a separate review. | High |
| Straight Tri-Lobe | Up to ~30 mm for soft solids, depending on model. Hard, incompressible particles: recommended ≤15 mm, subject to review. | Low to medium |
| Helical Tri-Lobe | Up to ~12 mm, depending on model; intended for small or no solids. | Pulsation-Free |
Straight Tri-Lobe
- Indicative Solids Passage
- Up to ~30 mm for soft solids, depending on model. Hard, incompressible particles: recommended ≤15 mm, subject to review.
- Discharge Pulsation
- Low to medium
Helical Tri-Lobe
- Indicative Solids Passage
- Up to ~12 mm, depending on model; intended for small or no solids.
- Discharge Pulsation
- Pulsation-Free
For coating, metal rotor, and seal compatibility, use the Materials Guide →
Next step
Match the Rotor Profile to Your Duty
Share the fluid, solids, and required flow behavior. The profile, material, pump size, and operating speed are selected together.
Request Pump Sizing
Send solids size and hardness, viscosity, flow, pressure, and any pulsation or product-sensitivity requirements.
Check Rotor Materials
Review rotor coverings and metal options against process chemistry, temperature, and cleaning conditions.
Prepare the Duty Data
Use the worksheet to organize flow, pressure, viscosity, solids, inlet conditions, and the operating cycle.