Priming is the process of filling the pump with water to remove air from the system and create the necessary suction for the pump to start drawing water effectively. For non-submersible pumps like centrifugal pumps or booster pumps, priming is essential to ensure the pump operates efficiently and prevents damage.
If the pump is not properly primed, it can lead to dry running, cavitation, or pump failure. Below is a step-by-step guide on how to properly prime your non-submersible pump.

1 Why Priming Is Necessary

• Air Removal: Non-submersible pumps rely on suction to draw water. Air in the system can prevent the pump from building up the required suction, causing it to fail to start or run inefficiently.
• Prevent Cavitation: Cavitation occurs when air bubbles enter the pump casing and implode, potentially damaging the impeller and other internal components. Priming helps avoid this.
• Pump Protection: Ensuring that the pump is filled with water prevents the motor from running dry, which could result in overheating and permanent damage.

2 How to Prime the Pump: Step-by-Step Process
1. Shut Off the Pump and Power Supply

• Why It’s Important: You need to ensure the pump is off to safely prime it without running the motor.
• What to Do:
  • Turn off the power supply to the pump at the control panel or disconnect switch to avoid any electrical hazards.

2. Open the Priming Valve (If Applicable)

• Why It’s Important: Most centrifugal pumps have a priming valve that allows you to fill the pump casing with water before starting the pump.
• What to Do:
  • Locate the priming valve on the pump. It is often a small valve near the pump casing or suction line.
  • Open the priming valve to allow water to enter the pump casing.
  • Make sure the water source (e.g., storage tank or pipe) is available for priming.

3. Fill the Pump with Water

• Why It’s Important: Filling the pump with water ensures that air is purged from the system, allowing the pump to generate suction.
• What to Do:
  • Slowly pour water into the priming valve until the pump casing is filled.
  • Allow the water to fill the pump, checking that the air is expelled from the system. You may hear air bubbles or gurgling as the air escapes.
  • Continue filling the pump until the casing is fully filled with water, and the air is no longer present.

4. Close the Priming Valve

• Why It’s Important: Closing the priming valve seals the pump, preventing any air from re-entering the system when the pump is started.
• What to Do:
  • Once the pump casing is filled with water, securely close the priming valve to prevent water from escaping.

5. Check the Suction Line

• Why It’s Important: Ensuring that the suction line is free of air and obstructions is key to maintaining pump efficiency.
• What to Do:
  • Inspect the suction line for air pockets, leaks, or debris that could block the flow of water to the pump.
  • If necessary, clear any obstructions from the suction pipe and check that all connections are tight and secure.

6. Turn On the Pump

• Why It’s Important: After the pump is primed, turning on the pump allows it to begin drawing water and operating under normal conditions.
• What to Do:
  • Turn on the pump’s power supply and activate the system.
  • Allow the pump to start drawing water and check that it is operating smoothly.
  • If the pump is properly primed, it should start generating suction immediately, and water should flow through the discharge pipe.

7. Check for Leaks and Air in the System

• Why It’s Important: Leaks or remaining air in the system can cause inefficiency, reduce pump performance, or lead to cavitation.
• What to Do:
  • After starting the pump, check the entire system for leaks, particularly around the pump casing, suction pipe, and discharge connections.
  • Listen for unusual noises (e.g., hissing or air bubbles), which can indicate that air is still in the system.
  • If air is present, repeat the priming process or troubleshoot any issues with the suction line.

3 Troubleshooting Common Priming Issues
1. Pump Fails to Prime

• Possible Causes:
  • Insufficient water supply to the pump.
  • Leaks in the suction line.
  • Blockages in the suction line or impeller.
  • Air trapped in the pump casing or suction line.
• What to Do:
  • Check the water supply to the pump to ensure it’s available and properly connected.
  • Inspect the suction line for leaks and tighten any loose connections.
  • Remove any blockages in the suction pipe, strainer, or impeller.
  • Check the priming valve to make sure it’s functioning correctly.

2. Pump Losing Prime After Start-Up

• Possible Causes:
  • Air entering the suction line after priming.
  • The pump is located too high above the water source (for suction lifts).
  • Leaks in the system causing air to enter.
• What to Do:
  • Check for any air leaks in the suction line or connections.
  • If the suction lift is too high, consider repositioning the pump closer to the water source or using a more powerful pump.
  • Inspect the foot valve or check valve for any signs of failure.

3. Water Not Flowing After Priming

• Possible Causes:
  • Clogged suction line or intake.
  • Insufficient water in the pump casing.
  • Incorrect pump speed or power issues.
• What to Do:
  • Ensure the suction line is clear of debris and blockages.
  • Recheck the priming process to ensure the pump is filled completely with water.
  • Verify that the pump is operating at the correct speed and that the motor is running efficiently.

4 Additional Tips for Successful Priming

• Check the NPSH (Net Positive Suction Head): Ensure that the pump is within the required NPSH parameters to avoid cavitation.
• Use a Vacuum Pump (If Needed): In some applications, especially with long suction lines, you may need to use a vacuum pump to assist in priming the system.
• Keep the Pump Clean: Ensure that the pump and suction line are clean to avoid debris that could interfere with the priming process.
• Inspect Regularly: Regularly check the pump, suction, and discharge lines for air leaks or blockages that could disrupt priming.

Priming a water pump, especially for non-submersible types like centrifugal or booster pumps, is an essential step to ensure the system starts up correctly and operates efficiently. By following the proper steps to fill the pump with water and remove air from the system, you prevent potential issues like dry running, cavitation, and damage to pump components. Regular checks and maintenance can help avoid common priming problems and ensure smooth, reliable pump operation. For more info contact Water Pump Suppliers in UAE or call us at +971 4 2522966.