These three terms describe different things, which is why they confuse buyers. Centrifugal is how the pump moves water: a spinning impeller throws water outwards and builds pressure. Submersible and monoblock describe the layout: where the pump sits and how its motor is joined to it.
Most submersible and monoblock pumps are centrifugal pumps. The question is really which layout suits your water source.
Centrifugal pumps
In the trade, "centrifugal pump" often means a surface pump on its own bearing frame, driven through a coupling by a separate motor or engine. This is the end-suction or bare-shaft pump.
The separate layout makes service easy. You can change the motor without touching the pump, or drive the pump from a diesel engine where there is no grid power. It takes more floor space and needs careful alignment between pump and motor.
Monoblock pumps
A monoblock pump puts the impeller directly on the motor shaft, so pump and motor form one compact block. There is no coupling to align, which makes installation simple and the unit cheaper to build.
Monoblocks sit on the surface and must lift water by suction. Practical suction lift is limited, usually a few metres, and falls further with altitude and warm water. They suit tanks, canals, shallow wells and transfer duties. If the motor fails, the whole block usually comes out together.
Submersible pumps
A submersible pump and its sealed motor run under water. Because the pump pushes water up instead of pulling it, there is no suction lift limit. The surrounding water also cools the motor.
There are two main kinds. Borewell submersibles are long and slim to fit a borehole, while openwell submersibles are horizontal and sit at the bottom of a well or sump. Both are explained in openwell and borewell submersible pumps.
Submersibles cost more to pull out for repair, need a suitable cable and control panel, and depend on good seals. Sand in the water wears them faster.
Which one to choose
- Choose a borewell submersible when the water is in a borehole or deeper than surface suction can reach.
- Choose an openwell submersible for wide wells and sumps where you want no priming and quiet running.
- Choose a monoblock for shallow sources, tanks and transfer where easy surface access matters.
- Choose a coupled centrifugal pump for larger flows, engine drive or where you want to service pump and motor separately.
Whichever layout you pick, size it from the duty point, not the motor rating. Our guide to choosing the right pump sets out the steps.
Next step
If you are unsure which layout your customers need, tell us the source, depth and flow. We will match it to makers who build that type well and check their test results. Book a free sourcing review.