What is air binding, and how can you avoid it when priming a pump?

What is air binding, and how can you avoid it when priming a pump?

• A. Air binding is water failing to prime due to air in suction; avoid by thorough priming, venting, ensuring complete water fill of suction line.
• B. Air binding is water spinning; avoid by closing suction.
• C. Air binding occurs when air compresses the pump; avoid by removing air from discharge.
• D. Air binding occurs only when using diesel engines.

Answer: (A)

Air binding happens on the suction side when air in the suction line or at the pump inlet prevents the water from filling the pump and establishing a proper prime. The pump tries to create a vacuum to lift water, but trapped air breaks the liquid column, so prime is lost and water cannot continue to flow. To avoid this when priming, remove that air and fill the suction path with water. This means thoroughly priming and venting the suction line, ensuring the entire suction line and pump casing are completely filled with water up to the eye of the impeller, and eliminating air pockets. Keep the connections tight and, if needed, use the vent/bleed valves to release any trapped air until a steady stream of water exits without sputtering. This is specifically about air in the suction side, not about air in the discharge, and it’s not about any particular engine type.

Air binding happens on the suction side when air in the suction line or at the pump inlet prevents the water from filling the pump and establishing a proper prime. The pump tries to create a vacuum to lift water, but trapped air breaks the liquid column, so prime is lost and water cannot continue to flow.

To avoid this when priming, remove that air and fill the suction path with water. This means thoroughly priming and venting the suction line, ensuring the entire suction line and pump casing are completely filled with water up to the eye of the impeller, and eliminating air pockets. Keep the connections tight and, if needed, use the vent/bleed valves to release any trapped air until a steady stream of water exits without sputtering.

This is specifically about air in the suction side, not about air in the discharge, and it’s not about any particular engine type.