Which pump do I need?
Pick your application and the whole package is sized at once on this one page: the right pump technology, the pump itself on real curves, its motor and gearbox, and the flowmeter and sensors to go with it. Click a different pump type at any point and everything below re-sizes on the same duty.
What is the pump for?
The fundamentals
The one decision that drives everything
Almost every pump selection starts with a single question: is this a centrifugal duty or a positive-displacement duty?
Centrifugal
Flow depends on pressure
An impeller flings liquid outward. Push against more head and you get less flow. Cheap, efficient and simple — as long as the liquid is thin and clean.
Choose it for water, effluent, cooling, boosting and irrigation at volume.
Positive displacement
Flow is set by speed
A fixed volume is carried per revolution, so flow stays constant no matter what the pressure does — and it does not care how thick the fluid is.
Choose it for viscous, shear-sensitive or solids-laden media, and for accurate dosing.
Five things that rule a centrifugal out
- →Viscosity. Flow and efficiency fall away fast as the fluid thickens — beyond a few hundred cP a centrifugal stops making sense.
- →Shear sensitivity. The impeller tears up polymer floc, emulsions and delicate product. PD pumps carry the fluid gently instead.
- →Solids. Rag and fibrous solids block impellers. You need a non-clog, a lobe, a PC or a hose pump.
- →Metering. Because centrifugal flow moves with system pressure, it cannot dose accurately. PD flow follows speed, so it can.
- →Suction lift. A centrifugal typically needs a flooded suction; PC, lobe, hose and diaphragm pumps are self-priming and need far less NPSH.
The technologies at a glance
| Pump type | Max viscosity | Solids | To bar | Best for |
|---|---|---|---|---|
| End-suction centrifugal | 500 cP | to 5 mm | 10 | The workhorse for clean liquid at volume. |
| Vertical multistage centrifugal | 200 cP | to 2 mm | 25 | High pressure from clean water. |
| Submersible non-clog | 500 cP | to 100 mm | 6 | Sits in the wet well and passes rag. |
| Progressive cavity | 1,000,000+ cP | to 60 mm | 48 | Constant flow through thick, gritty, delicate media. |
| Rotary lobe | 500,000 cP | to 50 mm | 12 | High flow, and serviced without disturbing the pipework. |
| Peristaltic (hose) pump | 100,000 cP | to 33 mm | 16 | Only the hose touches the fluid. |
| Air-operated double diaphragm | 50,000 cP | to 25 mm | 8 | Rugged, portable, air-driven. |
| Diaphragm metering pump | 5,000 cP | clean only | 20 | Precise low-flow chemical dosing. |
| Heavy-duty slurry centrifugal | 2,000 cP | to 50 mm | 12 | Lined and armoured for abrasive slurry at volume. |
| Self-priming centrifugal | 500 cP | to 40 mm | 6 | Sits above the liquid and pulls its own prime. |
| Vertical turbine / borehole | 200 cP | to 3 mm | 30 | Stacked bowls down a bore or wet pit. |
| Magnetic-drive centrifugal | 200 cP | clean only | 10 | Seal-less — there is nothing to leak. |
| Twin-screw pump | 500,000 cP | to 5 mm | 25 | High flow, near pulsation-free, thin or thick. |
| Internal gear pump | 250,000 cP | clean only | 16 | Compact, smooth flow for clean viscous liquids. |
| Piston / plunger pump | 20,000 cP | to 3 mm | 150 | Very high pressure at modest flow. |
| Sine / circumferential piston | 1,000,000+ cP | to 30 mm | 10 | The gentlest way to move delicate or chunky product. |
Figures are practical selection guides, not absolute limits — specialist executions exceed them. RDJ confirms the final technology, size and materials against your full process conditions.
Know the type? Size the pump.
Our selectors size the actual model against real manufacturer performance curves.