Industry-Knowledge

centrifugal pump impeller size chart

A centrifugal pump impeller size chart helps select the correct impeller diameter for desired flow rate, head (pressure), and efficiency. Since impeller sizing varies by pump model and manufacturer, here’s a general guide along with key considerations.


1. How Impeller Size Affects Pump Performance

  • Diameter (D) ↑ → Flow (Q) ↑, Head (H) ↑, Power (P) ↑

  • Trimming an impeller (reducing D) lowers performance but improves efficiency at partial loads.

Affinity Laws (for centrifugal pumps)

ChangeFlow (Q)Head (H)Power (P)
Speed (N) changeQ2=Q1×N2N1Q2=Q1×N1N2H2=H1×(N2N1)2H2=H1×(N1N2)2P2=P1×(N2N1)3P2=P1×(N1N2)3
Impeller (D) changeQ2=Q1×D2D1Q2=Q1×D1D2H2=H1×(D2D1)2H2=H1×(D1D2)2P2=P1×(D2D1)3P2=P1×(D1D2)3

2. Typical Impeller Diameter Ranges by Pump Type

Pump TypeImpeller Size Range (Diameter)Common Applications
End-Suction Pumps2" – 16" (50mm – 400mm)Water supply, HVAC, irrigation
Multistage Pumps4" – 12" (100mm – 300mm) per stageHigh-pressure boosting, boiler feed
Submersible Pumps3" – 14" (75mm – 350mm)Drainage, sewage, wells
API Process Pumps6" – 20" (150mm – 500mm)Oil & gas, chemical processing
Self-Priming Pumps5" – 12" (125mm – 300mm)Construction, dewatering

3. Example: Performance Chart for a 6x4 End-Suction Pump

(Flow in GPM, Head in ft, Impeller in inches)

Impeller Ø (in)Max Flow (GPM)Max Head (ft)HP Required
10.0"80015015 HP
9.5"70013512 HP
9.0"65012010 HP
8.5"6001057.5 HP
8.0"550905 HP

*(Note: Exact values depend on pump model & speed [1750/3500 RPM])*


4. How to Select the Right Impeller Size?

  1. Check the pump curve (provided by the manufacturer).

  2. Determine required flow (Q) & head (H) for your system.

  3. Match performance – Find where Q & H intersect on the curve.

  4. Trim impeller if needed (max 75% of original diameter).

Impeller Trimming Rules:

  • Do not exceed manufacturer’s max trim limit (usually 15-25% reduction).

  • Avoid trimming below minimum size (causes cavitation & inefficiency).

  • Re-balance impeller if trimmed significantly.


5. Common Impeller Sizing Mistakes

❌ Oversizing → Wasted energy, cavitation risk.
❌ Undersizing → Inadequate flow/pressure.
❌ Ignoring NPSH requirements → Cavitation damage.


6. Where to Find Manufacturer-Specific Charts?

  • Goulds, Grundfos, ITT, Sulzer, KSB – Check technical manuals.

  • Hydraulic Institute (HI) Standards – General guidelines.

The above content is compiled and published by Zhilong Drum Pump supplier, please specify, to buy oil drum pump, electric drum pump, high viscosity electric drum pump, fuel drum pump, food grade drum pump and so on, please contact us.