Calculator Inputs
Example Data Table
| Item | Sample Value |
|---|---|
| Design flow | 3.60 m³/h |
| Differential pressure | 6.00 bar |
| Rotor diameter | 65 mm |
| Pitch length | 85 mm |
| Stages | 4 |
| Entered speed | 320 rpm |
| Estimated displacement | 0.1334 L/rev |
| Actual flow at entered speed | 2.305 m³/h |
| Required rpm for design flow | 499.70 rpm |
| Motor power with service factor | 0.878 kW |
Formula Used
1. Flow area
Area = π × D² ÷ 4
2. Estimated displacement per revolution
Displacement = Area × Pitch × Fill Factor × Lobe Factor
3. Theoretical flow at entered speed
Theoretical Flow = Displacement × RPM × 60
4. Actual flow at entered speed
Actual Flow = Theoretical Flow × Volumetric Efficiency
5. Required speed for target flow
Required RPM = Design Flow ÷ (Displacement × 60 × Volumetric Efficiency)
6. Pressure split
Pressure Per Stage = Total Differential Pressure ÷ Number of Stages
7. Hydraulic power
Hydraulic Power = Pressure × Flow
8. Shaft power
Shaft Power = Hydraulic Power ÷ Mechanical Efficiency
9. Motor power
Motor Power = Shaft Power × Service Factor
10. Torque
Torque = (Pressure × Displacement) ÷ (2π × Mechanical Efficiency)
These are screening equations. Exact progressive cavity pump geometry changes by manufacturer, rotor profile, stator interference, elastomer type, and slip behavior.
How to Use This Calculator
- Enter the required flow and choose its unit.
- Enter the total differential pressure across the pump.
- Input rotor diameter, pitch, and current stage count.
- Set the operating speed used for the first check.
- Enter fluid specific gravity and viscosity.
- Adjust volumetric efficiency and mechanical efficiency if needed.
- Use fill factor and lobe factor to match your internal standard.
- Enter allowable pressure per stage and a motor service factor.
- Press calculate to show results above the form.
- Download the result table as CSV or PDF.
About Progressive Cavity Pump Design
Why this pump type is useful
Progressive cavity pumps move fluid with a rotating rotor inside a stator. They are strong choices for grout, sludge, paste, slurry, mortar, and other difficult fluids. Construction teams use them when steady flow matters. They also help when pulsation must stay low. This makes them useful for transfer, dosing, and dewatering support work.
What this calculator checks
This calculator gives a practical screening method. It estimates flow, displacement, required speed, torque, and power from basic geometry and duty data. It also checks pressure per stage. That stage check is important. A progressive cavity pump does not carry all pressure in one cavity. The pressure load is divided across stages. If pressure per stage becomes too high, wear and slip rise faster.
Why efficiency matters
The calculator uses volumetric efficiency and mechanical efficiency separately. Volumetric efficiency reduces the ideal flow. It reflects internal slip. Slip changes with pressure, stator condition, fluid temperature, and rotor fit. Mechanical efficiency affects torque and shaft power. This includes friction losses inside the pump and drive end. Keeping these two efficiencies separate gives a better design picture.
How geometry affects performance
Rotor diameter and pitch strongly influence displacement per revolution. Larger geometry usually gives more flow at the same speed. More stages usually increase pressure capability. Higher required speed can increase wear, heat, and stator stress. Thick fluids may need lower speed limits. That is why this tool includes a viscosity-based advisory speed check. It is not a final rule, but it is a useful design flag.
How to apply the output
Use these results for early selection, budgeting, and comparison. Then verify the chosen pump with supplier curves, elastomer compatibility, solids size, suction conditions, and test data. Final design should always be confirmed against real duty conditions. That step is essential for construction reliability and maintenance planning.
FAQs
1. Is this calculator suitable for final procurement?
No. It is best for screening and comparison. Final procurement should use supplier curves, rotor and stator geometry, elastomer data, solids limits, and actual test performance.
2. Why does the tool use fill and lobe factors?
Those factors let you tune the screening model. Progressive cavity geometry varies by manufacturer. The factors help match your internal estimating approach more closely.
3. What does pressure per stage tell me?
It shows how hard each stage is working. If pressure per stage is too high, slip, wear, heat, and stator loading can rise quickly.
4. Why is required rpm sometimes much higher than entered rpm?
That means the current geometry is small for the duty. You may need a larger rotor, longer pitch, better efficiency, or more than one pump.
5. Does viscosity always reduce flow?
Not always. Higher viscosity can reduce slip, but it can also raise friction and heating. This tool uses viscosity as a speed advisory, not a direct correction factor.
6. How should I choose volumetric efficiency?
Use plant data when available. For early checks, many designers start around 85% to 95%, then refine the value with test results and vendor input.
7. Can I use this for grout and mortar service?
Yes, for early sizing. You still need to confirm particle size, abrasiveness, hose losses, suction arrangement, and elastomer compatibility before approval.
8. Why is service factor included?
Service factor adds a safety margin to motor sizing. It helps cover duty variation, startup demand, wear growth, and normal construction operating uncertainty.