A waste water pump includes an impeller (12) and a surrounding pump housing (4), wherein an impeller side chamber (20) is formed between the impeller (12) and the pump housing (4). The impeller side chamber (20) has a first seal (16) between the impeller (12) and the pump housing (4), towards the intake side (32) of the impeller (12), and a second seal (18) between the impeller (12) and the pump housing (4), towards the pressure side (14) of the impeller (12). The first seal (16) is provided with a conveying device (28, 30) configured to convey debris from the impeller side chamber (20) to the intake side (32) of the impeller (12). The second seal (18) is provided with conveying device (38, 40) configured to convey debris from the side chamber (20) to the pressure side (14) of the impeller (12).

A fan device includes an impeller rotating around a central axis and a motor disposed farther downward than the impeller. The impeller includes a base unit enlarged downward and plural blades disposed on a peripheral surface of the base unit. Upper portions of the blades are positioned at a leading end of a rotating direction with respect to lower portions. In an outer end portion on a front surface of each blade at the leading end of the rotating direction, a radial-direction component of a normal unit vector of an upper end portion of the blade is smaller than that of a lower end portion, assuming that an outer peripheral side of the blade is a positive direction. A thickness of a root of the lower end portion is larger than that of the upper end portion.

A technique facilitates operation of a pump such as a multiphase pump. The pump may be provided with an impeller having a plurality of impeller blades. The impeller blades have blade tips which extend over an axial length. A ring is positioned along the blade tips to stiffen the impeller and to thus provide stability. However, the axial length of the ring is limited relative to the axial length of the impeller to enable flow, e.g. leakage, across the blade tips in a manner which causes active phase mixing during pumping of a fluid, e.g. a multiphase fluid.

An electric submersible pump having a housing with side walls and at least one stackable diffuser residing within the housing. The stackable diffuser can have a diffuser side wall forming an annular gap between the outer surface of the diffuser side wall and the inner surface of the housing side wall. A filler can be provided within the annular gap to prevent recirculation and/or rotation of the diffuser within the housing. Additionally or alternatively, an O-ring can be disposed within the annular gap to prevent recirculation and/or rotation of the diffuser within the housing.

A fan device includes an impeller rotating around a central axis and a motor disposed farther downward than the impeller. The impeller includes a base unit enlarged downward and plural blades disposed on a peripheral surface of the base unit. Upper portions of the blades are positioned at a leading end of a rotating direction with respect to lower portions. In an outer end portion on a front surface of each blade at the leading end of the rotating direction, a radial-direction component of a normal unit vector of an upper end portion of the blade is smaller than that of a lower end portion, assuming that an outer peripheral side of the blade is a positive direction. A thickness of a root of the lower end portion is larger than that of the upper end portion.

A waste water pump includes an impeller (12) and a surrounding pump housing (4), wherein an impeller side chamber (20) is formed between the impeller (12) and the pump housing (4). The impeller side chamber (20) has a first seal (16) between the impeller (12) and the pump housing (4), towards the intake side (32) of the impeller (12), and a second seal (18) between the impeller (12) and the pump housing (4), towards the pressure side (14) of the impeller (12). The first seal (16) is provided with a conveying device (28, 30) configured to convey debris from the impeller side chamber (20) to the intake side (32) of the impeller (12). The second seal (18) is provided with conveying device (38, 40) configured to convey debris from the side chamber (20) to the pressure side (14) of the impeller (12).