Abstract: A centrifugal pump, the impeller (2) of the pump having one or more holes through the impeller adjacent to its hub. The hole or holes (7) are positioned between the vanes (3) of the impeller and closer to the hub than the periphery of the impeller. The total area of the holes is more than 0.4% of the area of the impeller, preferably 0.5-0.6% of the area of the impeller or more than 2% of the inlet area of the pump, preferably 2.5-5% of the inlet area. Preferably there is a cavity or a pit (8) at the back of the impeller.

Abstract: The present invention is for a centrifugal pump, the impeller (2) of the pump having one or more holes through the impeller adjacent to its hub. The hole or holes (7) are positioned between the vanes (3) of the impeller (2) and closer to the hub than the periphery of the impeller. The total area of the holes is more than 0.4% of the area of the impeller, preferably 0.5-0.6% of the area of the impeller or more than 2% of the inlet area of the pump, preferably 2.5-5% of the inlet area. Preferably there is a cavity or a pit (8) at the back of the impeller.

Abstract: A centrifugal pump pumps fluid containing large or long objects of solid material. Solid parts cause problems with centrifugal pumps in that they both stick to the edge of the vanes of the pump wheel and get in between the pump wheel and the housing and stick to either one of these may cause the pump wheel to slow down or get stuck. Large parts may also form a bridge between two vanes. Objects which have become stuck to and rotate together with the pump wheel easily gather more objects and growth of the aggregate is often very rapid. In all of these cases the flow through the pump is distributed and the capacity of the pump is reduced. These problems are avoided with a centrifugal pump in which the edges of the vanes (11, 12, 13, 14) extend themselves continuously in the direction of the flow from the input adjacent the shaft and at an acute angle thereto to a lower part close to the wall (1-1A) of the housing and forwards in the direction of the flow of the pumped fluid.

Abstract: The present invention is for a conductivity metering device. The invention is primarily for conductivity meters which are used for level gauging of fouled liquids where the fouling materials may cause functioning problems of the metering probe. The probe is intended for metering of the conductivity between the probe body 1 and a tube 14, made from metallic material, in order to determine if there is liquid inside the tube. The probe body 1 is the outer tip of a piston 6 and it may be made as one piece with the piston or as a separate part which is mounted onto the piston. The piston 6 and parts connected thereto are movably mounted in the cover part 15 and the cap 8 by sealing slide bearings 4, 7. When metering does not take place the tube 14 is mostly filled with water at a certain overpressure relative to its surroundings. As the metering piston 6 is kept retracted by an active overpressure between the sealings 4 and 7 liquid is prevented from leaking in.

Abstract: The present invention is for an evacuation system which preferrably in its entirety is connected to and operates at the outlet side of a pump. The evacuation system is connected to the socket 5 by the connector 9 and one of the valves 15 or 16. In the evacuation system there is a compressor 19 and a pressurized air ejector 18. Air from the ejector exits through a pipe 24.

Abstract: In the disclosed method of determining the current or instantaneous operating conditions of a centrifugal pump, the radial forces impressed on the impeller shaft by the operatively rotating pump impeller are measured at a shaft-supporting bearing disposed proximate the pump housing and impeller. In a preliminary or test operation of the pump, this radial force measurement is taken at a plurality of volumetric liquid flow rates through the pump so as to develop a relationship between the radial force and liquid flow. Then, during normal operation of the pump, the current or instantaneous radial force is measured at the bearing and this measurement is compared to the previously-developed relationship to accurately determine the instantaneous operating conditions of the pump by identifying the point along the pump's characteristic curve--which defines for the pump a relationship between lifing height and volumetric liquid flow--at which the pump is currently operating.