Gear Pump GPM Calculator
A gear pump GPM calculator helps you quickly determine the flow rate of your pump in gallons per minute. It simplifies complex calculations and ensures accurate system design.
GPM Flow Calculator
How to Use a Gear Pump GPM Calculator
Follow these simple steps to use a gear pump GPM calculator effectively:
- 1Enter pump displacement: Input the pump displacement in cubic inches per revolution (in³/rev).
- 2Input pump speed: Enter the rotational speed in RPM (revolutions per minute).
- 3Add efficiency (optional but recommended): Use volumetric efficiency (typically 85%–95%).
- 4Click calculate: The calculator will display the flow rate in GPM.
- Always use correct units.
- Check manufacturer specifications.
- Include efficiency for real-world results.
How to Calculate Gear Pump GPM
You can calculate gear pump flow manually using this formula:
Where:
- Displacement = cubic inches per revolution
- RPM = pump speed
- Efficiency = decimal (e.g., 0.90 for 90%)
- 231 = cubic inches in one gallon
Step-by-Step Example
Given:
- Displacement = 2.5 in³/rev
- RPM = 1750
- Efficiency = 90% (0.90)
Step 1: Multiply displacement by RPM
2.5 × 1750 = 4375
Step 2: Multiply by efficiency
4375 × 0.90 = 3937.5
Step 3: Divide by 231
3937.5 ÷ 231 = 17.05 GPM
Final Answer: Flow Rate ≈ 17.05 GPM
Gear Pump GPM Conversion Chart
Assumptions: Efficiency = 100% (ideal condition)
| Displacement (in³/rev) | RPM | GPM |
|---|---|---|
| 1.0 | 1000 | 4.33 |
| 1.5 | 1200 | 7.79 |
| 2.0 | 1500 | 12.99 |
| 2.5 | 1750 | 18.94 |
| 3.0 | 1800 | 23.38 |
| 3.5 | 2000 | 30.30 |
| 4.0 | 2200 | 38.10 |
| 5.0 | 2500 | 54.11 |
Note: Multiply results by efficiency for real-world values.
Frequently Asked Questions (FAQs)
You can calculate the GPM of a gear pump by multiplying its displacement per revolution (in cubic inches) by its operating speed (RPM). Divide that total by 231 to convert cubic inches to gallons. Finally, multiply by the pump's volumetric efficiency to find the actual operating GPM.
The standard formula for calculating hydraulic pump GPM is: GPM = (Displacement × RPM) / 231. In this equation, displacement is measured in cubic inches per revolution. This theoretical GPM must then be adjusted for the pump's efficiency to determine the true output flow of the system.
To convert a pump's displacement from cubic centimeters (cc) to GPM, first convert cc to cubic inches by dividing by 16.387. Once you have the displacement in cubic inches, multiply it by the pump's RPM and then divide by 231 to obtain the theoretical flow rate in gallons per minute.
There is no single standard GPM for a hydraulic gear pump, as the flow rate depends entirely on the pump's specific displacement and rotational speed. Gear pumps are available in various sizes, delivering anywhere from a fraction of a GPM up to hundreds of gallons per minute for heavy use.
To size a gear pump for a specific GPM, determine the required flow rate and your motor's operating RPM. Multiply the target GPM by 231, and then divide that figure by the motor's RPM. The final result will give you the necessary pump displacement in cubic inches per revolution.