Hydraulic Pump Displacement Calculator

Hydraulic Pump Displacement Formula:

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

Displacement (Disp):

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1. What is Hydraulic Pump Displacement?

Hydraulic pump displacement refers to the volume of fluid that a pump can deliver per revolution of its input shaft. It is a critical parameter in hydraulic system design and determines the pump's flow output capacity at a given speed.

2. How Does the Calculator Work?

The calculator uses the hydraulic pump displacement formula:

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

Where:

\( Disp \) — Pump displacement (in³/rev)
\( Q \) — Flow rate (GPM)
\( RPM \) — Rotational speed (revolutions per minute)
\( \eta \) — Pump efficiency (unitless, 0-1)
231 — Conversion factor (cubic inches per gallon)

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

3. Importance of Pump Displacement Calculation

Details: Accurate displacement calculation is essential for proper hydraulic system design, pump selection, and ensuring the system meets performance requirements for flow, pressure, and power consumption.

4. Using the Calculator

Tips: Enter flow rate in GPM, RPM value, and pump efficiency (between 0 and 1). All values must be valid positive numbers with efficiency not exceeding 1.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the 231 conversion factor?
A: 231 is the number of cubic inches in one US gallon, which converts flow rate from gallons per minute to cubic inches per minute.

Q2: How does pump efficiency affect displacement?
A: Lower efficiency requires a larger displacement pump to achieve the same flow output, as some fluid is lost to internal leakage and other inefficiencies.

Q3: What are typical efficiency values for hydraulic pumps?
A: Gear pumps: 0.80-0.90, Vane pumps: 0.85-0.92, Piston pumps: 0.90-0.98. Efficiency varies with pressure, speed, and fluid viscosity.

Q4: Can this calculator be used for all pump types?
A: Yes, the formula applies to all positive displacement hydraulic pumps (gear, vane, piston) but efficiency values may differ significantly between pump types.

Q5: How does temperature affect the calculation?
A: Temperature affects fluid viscosity, which in turn affects pump efficiency. Higher temperatures generally reduce viscosity and may slightly improve efficiency for some pumps.