Pump Flow Rate Calculator
Calculate GPM and m³/h based on pipe diameter and fluid velocity.
Calculated Results:
Flow Rate (GPM): 0 GPM
Flow Rate (m³/h): 0 m³/h
Flow Rate (Liters/min): 0 L/min
Understanding the Pump Flow Rate Calculation Formula
When designing hydraulic systems or selecting a pump, determining the flow rate is the most critical step. Most engineering "pump flow rate calculation formula pdf" documents rely on the principle of continuity. This relates the velocity of the fluid to the cross-sectional area of the pipe it is traveling through.
Where:
Q = Flow Rate
V = Velocity of the fluid
A = Cross-sectional Area of the pipe (π × r²)
The GPM Calculation (US Standard)
In US standard units, we typically use Gallons Per Minute (GPM). To calculate GPM when you have the internal diameter of the pipe in inches and the velocity in feet per second (fps), use the following derived formula:
GPM = Velocity (fps) × Diameter² (inches) × 2.448
This constant (2.448) accounts for the conversion from cubic feet to gallons and the geometric calculation of the pipe's area.
Example Calculation
Imagine you have a pipe with an internal diameter of 3 inches and the fluid is moving at a velocity of 8 feet per second. What is the flow rate?
- Diameter = 3 inches
- Velocity = 8 fps
- Calculation: 8 × (3²) × 2.448
- 8 × 9 × 2.448 = 176.25 GPM
Typical Velocity Recommendations
Selecting the right velocity is key to preventing pipe erosion and minimizing pressure drop. Reference the table below for standard industry practices often found in design PDFs:
| Application | Recommended Velocity (fps) |
|---|---|
| Pump Suction Lines | 2 to 4 fps |
| Pump Discharge Lines | 5 to 10 fps |
| General Water Service | 4 to 7 fps |
| High Pressure Lines | 10 to 15 fps |
Why Flow Rate Calculations Matter
If the flow rate is calculated incorrectly, the pump may operate far from its Best Efficiency Point (BEP). This leads to cavitation, excessive vibration, and premature seal failure. By using the calculator above, engineers can ensure that the pipe diameter selected is appropriate for the desired flow volume without exceeding safe velocity limits.