An end suction close-coupled centrifugal pump is a common type of centrifugal pump where the impeller is directly mounted on the motor shaft (no coupling), and liquid enters axially at the suction side (end) and discharges radially. These pumps are widely used in water supply, HVAC, irrigation, and light industrial applications due to their compact design, ease of maintenance, and cost-effectiveness.
Design & Construction
Single-stage (one impeller)
Axial suction & radial discharge
Close-coupled (impeller mounted directly on motor shaft, eliminating the need for a coupling and baseplate)
Casing material options: Cast iron, stainless steel, bronze, or plastic (depending on fluid compatibility)
Advantages
Compact & space-saving (no separate bearing housing or coupling)
Lower initial cost (simpler design than frame-mounted pumps)
Easy installation & maintenance (fewer components)
Good for high-speed operation (direct motor connection)
Disadvantages
Limited to low-viscosity fluids (best for water-like viscosities)
Not ideal for high-temperature applications (motor heat can transfer to the pump)
Less flexibility (cannot easily change motor or impeller separately)
Flow Rate (Q): Typically 5 to 500 m³/h (varies by size & speed)
Head (H): Up to ~150 m (depends on impeller diameter & speed)
Power Range: 0.5 kW to 75 kW (common for close-coupled designs)
Best Efficiency Point (BEP): Operates best near the middle of the curve
Water supply & boosting
HVAC systems (chilled & hot water circulation)
Industrial processes (cooling, filtration, light chemicals)
Irrigation & drainage
Firefighting systems
Optimal for low-viscosity fluids (≤ 50 cP, like water, thin oils, chemicals).
Performance drops significantly above 100–200 cP.
For viscous fluids (e.g., oils, syrups), a positive displacement pump is better.
Check shaft alignment (though close-coupled reduces misalignment risk).
Monitor seal/bearing condition (mechanical seals or lip seals are common).
Avoid dry running (can damage seals & impeller).
Ensure proper NPSH (Net Positive Suction Head) to prevent cavitation.
| Feature | Close-Coupled | Frame-Mounted (Bearing Housing) |
|---|---|---|
| Design | Motor & pump share shaft | Separate shafts with coupling |
| Space | Compact | Larger footprint |
| Maintenance | Easier (fewer parts) | More complex (bearings, coupling) |
| Flexibility | Fixed motor-pump pairing | Motor can be changed independently |
| Vibration | More motor vibration transfer | Less vibration transfer |
End suction close-coupled centrifugal pumps are ideal for water-like fluids in compact, low-maintenance applications. However, for high-viscosity, high-temperature, or variable-speed needs, a frame-mounted pump or positive displacement pump may be more suitable.
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