Determining the Correct Horsepower for a Submersible Pump to Lift Water 150 Feet

When it comes to submersible pumps, understanding the required horsepower (hp) to lift water to a specific height is crucial for ensuring your system operates efficiently and effectively. This article aims to help you determine the HP needed for a submersible pump to lift water to a height of 150 feet.

Formula and Calculation

To calculate the required horsepower for a submersible pump, you can use the following formula:

Horsepower (Flow Rate (GPM) × Total Dynamic Head (TDH) × Specific Weight of Water) ÷ 3960

Let's break down the components:

Flow Rate (GPM): This refers to the gallons per minute you want to pump.

Total Dynamic Head (TDH): This is the vertical height in feet that the water needs to be lifted, in this case, 150 feet.

Specific Weight of Water: This is approximately 62.4 lbs/ft3.

Example Calculation

Assume you want to pump water at a rate of 10 gallons per minute (GPM).

Step 1: Convert GPM to lbs/min

Weight of water (lbs/min) GPM × 8.34 (weight of 1 gallon of water in lbs)

Weight of water (lbs/min) 10 GPM × 8.34 lbs/gallon 83.4 lbs/min

Step 2: Calculate Horsepower

Horsepower (83.4 lbs/min × 150 ft) ÷ 3960

Horsepower 12510 ÷ 3960 ≈ 3.16 HP

Conclusion

For a flow rate of 10 GPM to lift water to a height of 150 feet, you would need approximately 3.16 HP. However, it's important to note that this calculation does not account for efficiency losses in the pump or system. It is common to add a safety factor, usually around 1.25 to 1.5, to compensate for these inefficiencies. Therefore, you might consider a pump rated for around 4 HP or more in practical applications.

Note: This calculation is a simplified approach. For more accurate results, use an online calculator or consult with a professional.

Additional Considerations

A little more information is needed for a more precise calculation:

Flow rate required: This is the volume of water you need to pump per minute.

Suction head: This includes the vertical distance between the water surface and the pump's suction point.

System pressure required at the high point: This is the pressure needed at the point where the water reaches its highest point.

General Rule of Thumb

A general rule of thumb can be expressed by the equation:

HP psi x GPM x 0.0007 x S.G.

The use of this rule could be valuable in making an initial assessment. For water, the value for S.G. (specific gravity) is 1.0, simplifying our calculation:

Assume:

Discharge head from 150 ft high standpipe: 5 atmospheres or 75 psi.

Flow rate: 10 US GPM (Gallons per minute).

Calculated HP Requirement:

HP 75 psi × 10 GPM × 0.0007

HP ≈ 0.53