Design of airlift pumps for water circulation and aeration in aquaculture

Water flow rates were measured in airlift pumps 3·75-30 cm in diameter to develop performance data that might be useful to aquaculturists. Flows were determined when submergence of airlifts was 100% and when the center-line of the discharge was between 12·5 cm above and 5 cm below the water surface. Air was injected at 15-cm intervals from 15 cm to 120 cm below the discharge of the airlift and air flow was varied from 28 to 1416 liters min⁻¹. An increase in the vertical lift reduced flow rates greatly in large-diameter pipes, but only slightly affected flow rates in small-diameter pipes. Water flow increased linearly as air flow increased logarithmically.