Well Pump HP Calculator

Well Pump HP Formula:

\[ HP = \frac{Q \times H \times SG}{3960 \times \eta} \]

Flow Rate (Q):

GPM

Total Head (H):

feet

Specific Gravity (SG):

(dimensionless)

Pump Efficiency (η):

(decimal)

Pump Horsepower (HP):

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1. What is the Well Pump HP Formula?

The well pump horsepower formula calculates the required power to move water through a system based on flow rate, total head, specific gravity, and pump efficiency. It's essential for proper pump selection and system design.

2. How Does the Calculator Work?

The calculator uses the pump horsepower equation:

\[ HP = \frac{Q \times H \times SG}{3960 \times \eta} \]

Where:

\( Q \) — Flow rate in gallons per minute (GPM)
\( H \) — Total head in feet
\( SG \) — Specific gravity of fluid (1.0 for water)
\( \eta \) — Pump efficiency (typically 0.7-0.9)
3960 — Conversion factor (foot-pounds per minute per horsepower)

Explanation: The equation calculates the power required to move a specific volume of fluid against a certain head pressure, accounting for the pump's efficiency.

3. Importance of Pump HP Calculation

Details: Proper pump sizing is crucial for energy efficiency, system longevity, and preventing cavitation or overload conditions. Undersized pumps won't meet demand, while oversized pumps waste energy and may cause premature wear.

4. Using the Calculator

Tips: Enter flow rate in GPM, total head in feet, specific gravity (1.0 for water), and pump efficiency as a decimal (e.g., 85% = 0.85). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is total head in pump calculations?
A: Total head is the sum of static head (vertical distance), friction head (pipe resistance), and pressure head (system pressure requirements).

Q2: What's a typical pump efficiency value?
A: Centrifugal pumps typically range from 70-90% efficiency. Submersible pumps often have higher efficiency (80-90%) than jet pumps (60-75%).

Q3: Why is specific gravity important?
A: Specific gravity accounts for fluid density. Water is 1.0, while more dense fluids require more power to pump.

Q4: Should I add a safety factor to the calculated HP?
A: Yes, it's common to add 10-20% to account for system variations and future demands when selecting a pump.

Q5: How does this relate to electrical power requirements?
A: Electrical input power will be higher due to motor efficiency. Divide HP by motor efficiency (typically 0.8-0.95) to estimate electrical requirements.