AbstractThe amount of flowing air held up, or retained, under the surface of water and corn syrup solutions was measured in cylindrical tanks of different sizes using turbine type mixing impellers. Holdup is frequently used as an index of the effectiveness of gas‐liquid contacting in adsorption or stripping operations; it can be correlated with air flow rate and power input as followsh = a(PT/V)bFcwherehis the holdup of air in ft. per ft. of ungassed liquid,a, b, andc, are constants, (PT/V) is the total power supplied by the impeller and air per unit volume, andFis the superficial velocity of the air. Values ofaandbvary with tank size. The effect of liquid viscosity is pronounced but not amenable to simple correlations with the constants.Limits of operation to prevent flooding are defined as functions of impeller power and air flo