Abstract: The performance of a double-cone device (1) is increased, not only by moving the gap or inlet openings (22) a short distance into the exit cone (47), but also by making the conicity ?3 (55) of the so-formed small diffuser less than the conicity ?2 (109) of the remaining part (53) of the exit cone. Double cone units (7, 60), particularly the ones with this improved diffuser, may be used in pump installations (1, 60), like well-pumps (1), where liquids must be pumped from great depths.

Abstract: The lifetime of a double-cone device (21) for creating a pressure difference in a streaming fluid can be greatly increased by moving the inlet gap (5) into the exit cone (4). This results in a short so-called diffuser (22) being obtained between the gap (5) and the orifice (19), where entry cone (3) and exit cone (4) are connected. The increased lifetime permits the double-cone device to cope with much higher flow rates. Thus higher system pressures are created which enhance the use of the double-cone for such applications as the desalination of sea water by reverse osmosis. The important application of the seperation of oil from water using a separating device such as a cyclone (57) working under elevated pressure is now feasible. The increased power of the double-cone permits one to profit more fully from the new concept of reduction of the concentration of the feed supplied to the double-cone device (21).