| 摘要 |
A centrifugal pump wheel (4) comprises a rear (6) and/or a front (9) covering plate or dish, which has a plurality of gas evacuation openings (8) located leeward of the pump wheel vanes (5). To increase the effectivity of the gas evacuation and thereby improve the performance characteristics of the pump that fraction of the area of the openings which is located nearer the circumference of the pump wheel than the center of the pump wheel has been made larger than the remaining portion of the area of the openings. The invention also relates to a method of pumping a liquid which contains gas and possibly also solids, by means of a centrifugal pump having a pump wheel with the above characteristics. The gas pressure in a conduit (12) which is in communication with said openings (8) is measured. The measured value is compared with the liquid pressure in the pump inlet, and the pressure difference between said pressures is utilized to control a valve (13) in said conduit in such a manner that said pressure difference and/or the difference between the pressure in the pump inlet (2) and the pump outlet (3) is maintained within pre-determined limits. |
