Water Pump Selection in Practice: Choose the Right Pump to Avoid Waste

Water Pump Selection in Practice: Choose the Right Pump to Avoid Waste 

Choosing the wrong pump can lead to anything from wasting fuel and electricity to failing to pump water and damaging equipment. You only need to focus on these three core indicators to make the right choice.

Indicator 1: Head – Determining “Whether the Pump Can Be Pumped Up”

This is the most important indicator. Head is not the pumping height, but rather the total head loss the pump needs to overcome.

Practical Calculation Formula:

Actual Required Head = Vertical Lifting Height (meters) + Losses Due to Horizontal Transport Distance (meters) + Pipeline Accessory Losses (meters)

Vertical Lifting Height: The vertical height difference from the surface of the moving water source to the center of the outlet.

Horizontal Losses: Usually estimated at 10%-20% of the horizontal distance (take a larger value for smaller pipe diameters and more bends).

Accessory Losses: Each bend and valve increases resistance, approximately equal to the horizontal pipe loss over several meters to tens of meters.

Golden Rule for Pump Selection:

**Pump Rated Head = (1.1 ~ 1.2) × Actual Required Head**

Leave a 10%-20% margin to accommodate changes in resistance and efficiency reduction. However, avoid excessively high head, as this will lead to excessive flow, motor overload, and a sharp drop in efficiency.

**Indicator Two: Flow Rate – Determines "Sufficient and Fast"**

Flow rate refers to the amount of water output per unit time, determined by your actual needs.

Practical Determination Method:

**Irrigation Needs:** Calculate based on crop type, area, daily water requirement, and planned irrigation time.

**Domestic Water Supply:** Estimate the total flow rate of devices using water simultaneously (faucets, showers, washing machines).

Common Reference:** Household well pumps with a flow rate of 1-3 cubic meters per hour (approximately 16-50 liters per minute) typically meet the needs of most yards and households.

Selection Notes:

While meeting the head requirement, choose a pump with a rated flow rate slightly greater than your required flow rate. Flow rate and head together determine the pump's operating point.

Indicator 3: Pump Type and Power – Determining Suitability and Economy

The first two indicators determine performance; this one determines matching degree and energy efficiency.

1. Select Type Based on Water Source and Structure:

For pumping water from deep wells (>8 meters): A submersible pump is essential, with the motor submerged in water for high head.

For pumping water from rivers, ponds, or shallow wells: A self-priming centrifugal pump is preferred for easy starting.

For high-flow, low-head water delivery (e.g., river/pond irrigation): Consider an axial-flow pump or mixed-flow pump.

2. Select Power Based on Energy Conditions:

For stable mains power: A single-phase or three-phase electric pump is preferred for low operating costs and low noise.

For field operations without electricity: Only a diesel engine pump can be selected, providing its own power, but it is noisy and complex to maintain.

Quick Reference Process:

Measure/calculate your "actual required head" and "demanded flow rate."

Determine the pump type (submersible pump/centrifugal pump, etc.) based on the water source. Check the product nameplate or flow chart to find a water pump whose rated head and flow rate cover your calculated values, and whose operating point is in the middle of the pump's high-efficiency range.

Determine the power source (electric/diesel) based on site conditions.

Finally, a word of advice: It's better to spend more time calculating than to buy based on intuition. A water pump with a properly matched head and flow rate will save you far more in electricity and fuel costs over the long term than the effort you put into selecting it. Remember: Choosing the right pump is the greatest energy saving.