Gear Pump Size Calculator

Gear Pump Displacement Formula:

\[ Disp = \frac{Q \times 231}{RPM \times \eta} \]

Displacement (Disp):

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1. What is the Gear Pump Displacement Formula?

The gear pump displacement formula calculates the required displacement size of a gear pump based on flow rate, rotation speed, and efficiency. It's essential for proper hydraulic system design and pump selection.

2. How Does the Calculator Work?

The calculator uses the gear pump displacement formula:

\[ Disp = \frac{Q \times 231}{RPM \times \eta} \]

Where:

\( Disp \) — Pump displacement (in³/rev)
\( Q \) — Flow rate (GPM)
\( RPM \) — Rotation speed (RPM)
\( \eta \) — Efficiency (unitless, 0-1)

Explanation: The formula calculates the volumetric displacement per revolution needed to achieve a specific flow rate at a given speed, accounting for pump efficiency.

3. Importance of Gear Pump Sizing

Details: Proper pump sizing is crucial for system efficiency, preventing cavitation, ensuring adequate flow and pressure, and extending pump life. Undersized pumps can't meet flow requirements, while oversized pumps waste energy and increase costs.

4. Using the Calculator

Tips: Enter flow rate in GPM, rotation speed in RPM, and efficiency as a decimal between 0 and 1. All values must be positive numbers with efficiency not exceeding 1.0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 231 used in the formula?
A: The constant 231 converts gallons to cubic inches (1 gallon = 231 cubic inches), allowing the formula to output displacement in in³/rev.

Q2: What is a typical efficiency value for gear pumps?
A: Gear pump efficiency typically ranges from 0.80 to 0.95 (80-95%), depending on pump design, operating conditions, and fluid properties.

Q3: Can this formula be used for other pump types?
A: While the basic principle applies to positive displacement pumps, specific efficiency characteristics vary by pump type (vane, piston, etc.).

Q4: How does viscosity affect pump efficiency?
A: Higher viscosity fluids generally reduce pump efficiency due to increased internal friction and leakage losses.

Q5: What if I need to calculate flow rate from displacement?
A: The formula can be rearranged: \( Q = \frac{Disp \times RPM \times \eta}{231} \)