Pumps and Systems

Stainless Steel Single-Stage Centrifugal Pump: Working Principle and Selection Guide

We explain step by step how single-impeller stainless steel centrifugal pumps work, how they differ from multistage pumps and where they are the right choice.

ORFA Technical TeamUpdated: Oct 30, 20263 min read

Stainless steel single-stage centrifugal pump

Transferring clean, hygienic or mildly corrosive liquids at moderate pressures is one of the most common needs in industrial and domestic applications. A stainless steel single-stage centrifugal pump works with a single impeller, has wetted parts made of stainless steel and offers a simple, durable design.

This article explains step by step how a single-stage pump works, how it differs from multistage pumps, what its benefits are and where it is the right choice.

What Is a Stainless Steel Single-Stage Centrifugal Pump?

“Single-stage” means that the pump adds energy to the liquid with only one impeller. These pumps are usually end-suction pumps with a volute casing. The casing, impeller and other wetted parts are typically made of AISI 304 or AISI 316L stainless steel, providing hygiene and corrosion resistance.

Working Principle

Inlet: The liquid enters through the suction nozzle into the centre (eye) of the impeller.
Rotation: The motor drives the impeller.
Centrifugal action: The rotating vanes accelerate the liquid radially towards the outer edge of the impeller.
Energy increase: On leaving the impeller, both the velocity and the pressure of the liquid have increased.
Conversion to pressure: The volute casing, with its gradually widening cross-section, slows the liquid and converts part of its kinetic energy into pressure.
Discharge: The pressurised liquid is delivered to the system through the discharge nozzle.

Single-Stage vs Multistage Pumps

Feature	Single-stage	Multistage
Number of impellers	One	Two or more in series
Head	Low to medium	High (increases with number of stages)
Design and maintenance	Simple, few parts	More complex
Tolerance to dirty liquids	Relatively better	More sensitive due to narrow passages
Typical use	Transfer, circulation, irrigation	Booster sets, boiler feed, high-pressure washing

Benefits

Hygiene: The stainless steel surface is easy to clean and suits hygiene-sensitive applications.
Corrosion resistance: High resistance to water and many chemicals.
Versatility: Suitable for clean water, slightly dirty water and chemicals compatible with stainless steel.
Efficient operation: When selected correctly, energy consumption is low around the best efficiency point.
Durability: Stainless material and a simple design ensure long life.
Easy installation and maintenance: The compact design makes installation and servicing easy.

Applications

Water supply and pressure boosting
HVAC and air-conditioning systems
Industrial cooling and heating circuits
Agricultural irrigation
Food and beverage industry
Pharmaceutical industry
Chemical industry (after checking material compatibility)

Tip: If the required head exceeds what a single-stage pump can deliver, a multistage pump may be the more efficient solution. Always check flow, head, temperature and pressure limits in the data sheet of the selected model.

Selection Checklist

Required flow and total head including system losses
Liquid temperature and chemistry, and accordingly AISI 304 or 316L
Maximum operating pressure and temperature (per data sheet)
Motor power, supply voltage and protection class
Suction conditions and NPSH margin

Frequently Asked Questions

What does single-stage pump mean?

It is a pump in which energy is added to the liquid by a single impeller. In multistage pumps several impellers are connected in series, and the head increases with the number of stages.

Should I choose AISI 304 or AISI 316L?

AISI 304 is usually sufficient for clean water and many food applications. For chloride-containing water and more aggressive liquids, molybdenum-alloyed AISI 316L offers better corrosion resistance.

Can a stainless steel single-stage pump handle hot water?

Yes, it can be used in heating circuits. The maximum liquid temperature depends on the model and the mechanical seal material.

Conclusion

With their simple design, hygienic materials and wide range of uses, stainless steel single-stage centrifugal pumps are a reliable solution for moderate-pressure liquid transfer. Selected with suitable materials and the right duty point, they deliver many years of efficient service. Browse our stainless steel centrifugal pumps page for available models, or ask the ORFA sales team for advice on your application.

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