1. What is a GPM to HP Calculator?

Definition: This calculator estimates the horsepower required based on flow rate (GPM), head (ft), and pump efficiency.

Purpose: It helps engineers and technicians determine the power requirements for pumping systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( HP \) — Horsepower
• \( Q \) — Flow rate (gallons per minute)
• \( H \) — Total head (feet)
• \( \eta \) — Pump efficiency (0-1)
• 8.34 — Weight of water (lbs/gallon)
• 3960 — Conversion constant (ft-lb/min per HP)

Explanation: The formula calculates the power needed to move water against gravity and system resistance.

3. Importance of HP Calculation

Details: Proper horsepower estimation ensures correct pump sizing, energy efficiency, and system reliability.

4. Using the Calculator

Tips: Enter the flow rate in GPM, total head in feet, and pump efficiency (default 0.85). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical pump efficiency value?
A: Most pumps operate between 70-90% efficiency (0.7-0.9). The default 0.85 represents a typical value.

Q2: Does this calculate brake horsepower or water horsepower?
A: This calculates brake horsepower (actual power required) which includes pump efficiency.

Q3: What if I'm pumping something other than water?
A: Multiply the result by the specific gravity of your fluid (water = 1.0).

Q4: How do I find total head?
A: Total head is the sum of static head, friction losses, and pressure head in the system.

Q5: Should I round up the HP result?
A: Yes, typically select the next available motor size above your calculated HP.