How To Calculate Hydraulic Pump Size

Hydraulic Pump Size Formula:

\[ \text{Size\_pump} = \frac{Q\_req}{RPM \times \eta / 231} \]

Flow Rate Required (Q_req):

gallons per minute

Revolutions Per Minute (RPM):

RPM

Efficiency (η):

(0 to 1)

Pump Size (Size_pump):

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1. What Is Hydraulic Pump Size Calculation?

The hydraulic pump size calculation determines the required displacement volume of a hydraulic pump based on the desired flow rate, operating speed, and system efficiency. This is essential for proper hydraulic system design and component selection.

2. How Does The Calculator Work?

The calculator uses the hydraulic pump size formula:

\[ \text{Size\_pump} = \frac{Q\_req}{RPM \times \eta / 231} \]

Where:

\( Size\_pump \) — Pump displacement (cubic inches per revolution)
\( Q\_req \) — Required flow rate (gallons per minute)
\( RPM \) — Pump speed (revolutions per minute)
\( \eta \) — Pump efficiency (unitless, 0 to 1)
231 — Conversion factor (cubic inches per gallon)

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

3. Importance Of Pump Size Calculation

Details: Proper pump sizing is critical for hydraulic system performance, energy efficiency, and component longevity. Undersized pumps can't deliver required flow, while oversized pumps waste energy and increase costs.

4. Using The Calculator

Tips: Enter the required flow rate in gallons per minute, the pump operating speed in RPM, and the pump efficiency as a decimal between 0 and 1. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical efficiency value for hydraulic pumps?
A: Efficiency varies by pump type: gear pumps typically 80-90%, vane pumps 85-92%, piston pumps 90-98%. Always consult manufacturer specifications.

Q2: Why is the conversion factor 231 used?
A: 231 is the number of cubic inches in a US gallon, which converts flow rate (GPM) to displacement (cubic inches per revolution).

Q3: Can this formula be used for all pump types?
A: Yes, the formula applies to all positive displacement hydraulic pumps (gear, vane, piston), though efficiency values will differ.

Q4: How does temperature affect pump efficiency?
A: Higher temperatures typically reduce efficiency due to increased internal leakage and reduced viscosity. Efficiency values should be based on operating temperature.

Q5: What if my pump operates at variable speeds?
A: For variable speed applications, use the minimum expected RPM in calculations to ensure adequate flow at all operating conditions.