A pump is delivering at less than the expected rate of discharge. What will not cause this to happen?

A pump is delivering at less than the expected rate of discharge. What will not cause this to happen?

• A. Check valve stuck or clogged.
• B. Discharge head too low.
• C. Impeller clogged.
• D. Pump not primed.

Answer: (B)

When a pump is delivering less than the expected discharge, think about what can restrict the flow or prevent the pump from moving water. If the discharge head is too low, there’s actually less resistance for the water to overcome in the discharge piping, so the pump would either deliver more water or at least not be limited by the piping. That means a low discharge head does not cause reduced discharge. Other factors that do reduce discharge include a check valve that’s stuck or clogged, which creates backpressure and blocks flow; an impeller that’s clogged, which can't transfer energy effectively to the water; and a pump that isn’t primed, which can’t develop the suction needed to draw water in.

When a pump is delivering less than the expected discharge, think about what can restrict the flow or prevent the pump from moving water. If the discharge head is too low, there’s actually less resistance for the water to overcome in the discharge piping, so the pump would either deliver more water or at least not be limited by the piping. That means a low discharge head does not cause reduced discharge.

Other factors that do reduce discharge include a check valve that’s stuck or clogged, which creates backpressure and blocks flow; an impeller that’s clogged, which can't transfer energy effectively to the water; and a pump that isn’t primed, which can’t develop the suction needed to draw water in.