Gas binding in a pump system is most commonly caused by which of the following?

Gas binding in a pump system is most commonly caused by which of the following?

• A. Cavitation
• B. Inadequate venting or entrained gases in the liquid
• C. Excessive prime
• D. High ambient temperature

Answer: (B)

Gas binding occurs when pockets of gas on the suction side prevent the pump from being fully filled with liquid, so the impeller tries to move air rather than liquid and cannot develop the necessary suction to lift the fluid. The most common cause is inadequate venting or entrained gases in the liquid. If the suction line isn’t properly vented, dissolved gases come out of solution as the liquid is drawn into the pump, forming air pockets that break the liquid column and cause loss of prime. Cavitation is a related phenomenon but it’s driven by local pressure dropping below the liquid’s vapor pressure and forms vapor bubbles inside the pump itself, not by gas trapped in the suction line. The other options aren’t typical root causes: high ambient temperature or excessive prime don’t directly create the suction-side gas pockets that cause binding.

Gas binding occurs when pockets of gas on the suction side prevent the pump from being fully filled with liquid, so the impeller tries to move air rather than liquid and cannot develop the necessary suction to lift the fluid. The most common cause is inadequate venting or entrained gases in the liquid. If the suction line isn’t properly vented, dissolved gases come out of solution as the liquid is drawn into the pump, forming air pockets that break the liquid column and cause loss of prime. Cavitation is a related phenomenon but it’s driven by local pressure dropping below the liquid’s vapor pressure and forms vapor bubbles inside the pump itself, not by gas trapped in the suction line. The other options aren’t typical root causes: high ambient temperature or excessive prime don’t directly create the suction-side gas pockets that cause binding.