Abstract: 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.

Abstract: A throttling device for restricting the flow of flushing fluid from a source of supply through a mechanical seal in which the throttle includes two members which are rotatably connected in fluid-tight relationship with respect to one another and which have a plurality of fluid flow openings there through which are symmetrically located about a common axis and which are selectively aligned to create varying fluid flow paths of varying diameters so that the flushing fluid is selectively channeled therethrough to an eddy current chamber within one of the members which serves to further restrict the flow of fluid with respect to the seal.