Gear Pump Sizing Calculator

Gear Pump Displacement Formula:

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

Displacement Size (Disp_size):

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1. What is Gear Pump Displacement?

Gear pump displacement refers to the volume of fluid that a gear pump can theoretically deliver per revolution. It is a critical parameter in hydraulic system design and pump selection, determining the pump's flow capacity at a given speed.

2. How Does the Calculator Work?

The calculator uses the gear pump displacement formula:

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

Where:

\( Disp\_size \) — Displacement size (in³/rev)
\( Q \) — Flow rate (GPM)
\( RPM \) — Rotational speed (RPM)
\( \eta \) — Pump efficiency (unitless, 0-1)

Explanation: The formula calculates the theoretical displacement required to achieve a specific flow rate at given RPM, accounting for pump efficiency.

3. Importance of Proper Pump Sizing

Details: Correct pump sizing is essential for system efficiency, preventing cavitation, ensuring adequate flow and pressure, and extending pump life. Oversized or undersized pumps can lead to energy waste, system instability, and premature failure.

4. Using the Calculator

Tips: Enter flow rate in GPM, rotational speed in RPM, and pump 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 for consistent units in the calculation.

Q2: What is typical efficiency for gear pumps?
A: Gear pump efficiency typically ranges from 0.7 to 0.9 (70-90%), depending on design, operating conditions, and fluid properties.

Q3: Can this calculator be used for other pump types?
A: This specific formula is designed for gear pumps. Other pump types (vane, piston, etc.) may have different displacement characteristics and calculation methods.

Q4: How does temperature affect pump efficiency?
A: Temperature affects fluid viscosity, which in turn impacts pump efficiency. Higher temperatures generally reduce viscosity and may affect efficiency calculations.

Q5: What if I need to calculate for metric units?
A: For metric units (L/min and cm³/rev), a different conversion factor would be needed. The basic principle remains the same but requires appropriate unit conversions.