An airlock in a centrifugal pump prevents it from priming and pumping fluid effectively. Here's how to remove it:
Methods to Remove Airlock
There are several methods to try, depending on the pump and system setup. Start with the simplest and progress to more involved techniques.
1. Priming the Pump
This is the most common solution and often the easiest. Centrifugal pumps need to be primed because they cannot pump air.
- Turn off the power: Ensure the pump is de-energized for safety.
- Locate the priming port: This is usually a capped opening on the pump casing.
- Remove the cap: Carefully unscrew or remove the cap.
- Fill the pump casing with liquid: Slowly pour liquid (usually water) into the priming port until the pump casing and suction line are completely full. This displaces the air.
- Replace the cap: Securely tighten the priming port cap.
- Turn on the power: Start the pump and observe if it begins pumping fluid. If not, repeat the priming process.
2. Backflushing the Suction Line
This technique helps dislodge air trapped in the suction line.
- Isolate the pump: Close any valves on the discharge side of the pump.
- Introduce liquid under pressure: Use a hose connected to a pressurized water source (like a garden hose) to force water back through the suction line, from the pump towards the source. This helps push any air pockets out.
- Open the discharge valve slowly: Once you hear water flowing freely, slowly open the discharge valve.
- Monitor the pump's performance: Check to see if the pump is now operating normally.
3. Venting the Pump
Some pumps have a vent valve or screw that allows you to release trapped air.
- Locate the vent valve: Look for a small valve or screw on the top of the pump casing.
- Open the vent valve: Slowly open the valve or loosen the screw.
- Allow air to escape: Let the trapped air escape until liquid starts to come out.
- Close the vent valve: Securely close the valve or tighten the screw.
- Start the pump: Turn on the pump and observe its operation.
4. Using a Foot Valve
A foot valve at the end of the suction pipe (inside the liquid source) helps maintain prime by preventing liquid from draining back out of the suction line when the pump is off. Ensure the foot valve is functioning correctly. If it's leaking, it could be allowing air to enter the system.
5. Checking for Leaks in the Suction Line
Even small leaks in the suction line can allow air to enter the system and cause airlocks. Inspect all connections, fittings, and the suction pipe itself for any signs of leaks. Repair or replace any damaged components.
6. Elevating the Suction Line
If possible, slightly elevating the suction line towards the pump can help prevent air from becoming trapped in low spots.
7. Disassembling and Inspecting the Pump (Advanced)
If the above methods fail, you may need to disassemble the pump to inspect the impeller and casing for damage or obstructions that could be contributing to the airlock. This is detailed by the steps found on Quora, but this is a more technical solution to undertake:
- Turn off the power.
- Remove pipe connections.
- Disconnect the pump.
- Dismantle the centrifugal pump's impeller.
- Replace the seal (if necessary).
- Screw on the impeller.
- Reconnect the pump.
Important Considerations:
- Safety First: Always disconnect the power supply before working on any pump.
- Pump Type: The specific method for removing an airlock may vary slightly depending on the type and model of the centrifugal pump. Consult the pump's manual for specific instructions.
- Persistent Airlocks: If you frequently experience airlocks, there may be an underlying issue with the system design or pump installation that needs to be addressed.
