Abstract: An apparatus and method for mixing a liquid having particulate includes a vessel for containing me liquid an axial impeller rotating about a substantially vertical axis. The impeller is adapted for submerging below the liquid surface by a distance approximately one-quarter to one-half of the height of the liquid. The impeller is oriented upwardly to produce (a) an inner, upward flow region located along the vertical axis of the vessel, (b) a transition flow region above the impeller in which liquid moves radially outwardly toward the vessel sidewall, and (c) an outer, downward flow region located along the sidewall. The impeller spins at a variable speed, such that the flow is capable of entraining solid particles having a settling velocity of up to approximately 1 foot per minute in the liquid, and the speed of the impeller is chosen to enable particles having a desired settling velocity to settle to the vessel bottom.

Abstract: An apparatus and method for mixing a liquid having particulate includes a vessel for containing me liquid an axial impeller rotating about a substantially vertical axis. The impeller is adapted for submerging below the liquid surface by a distance approximately one-quarter to one-half of the height of the liquid. The impeller is oriented upwardly to produce (a) an inner, upward flow region located along the vertical axis of the vessel, (b) a transition flow region above the impeller in which liquid moves radially outwardly toward the vessel sidewall, and (c) an outer, downward flow region located along the sidewall. The impeller spins at a variable speed, such that the flow is capable of entraining solid particles having a settling velocity of up to approximately 1 foot per minute in the liquid, and the speed of the impeller is chosen to enable particles having a desired settling velocity to settle to the vessel bottom.

Abstract: An apparatus and method for mixing a liquid having particulate includes a vessel for containing the liquid and an axial impeller rotating about a substantially vertical axis. The impeller is adapted for submerging below the liquid surface by a distance approximately one-quarter to one-half of the height of the liquid. The impeller is oriented upwardly to produce (a) an inner, upward flow region located along the vertical axis of the vessel, (b) a transition flow region above the impeller in which liquid moves radially outwardly toward the vessel sidewall, and (c) an outer, downward flow region located along the sidewall. The impeller spins at a variable speed, such that the flow is capable of entraining solid particles having a settling velocity of up to approximately 1 foot per minute in the liquid, and the speed of the impeller is chosen to enable particles having a desired settling velocity to settle to the vessel bottom.

Abstract: An impeller assembly includes a shaft, multiple scoops spaced circumferentially about the shaft, each scoop including an upper blade portion and a lower blade portion, spaced apart at the leading edges and joined at the inner edges, and a rib extending rearward from the inner edges, each scoop being coupled to the shaft by attachment at the rib. A system and method for mixing gas or liquid into liquid include a vessel for containing liquid, a drive shaft for extending into the vessel, and an impeller assembly adapted for rotating about the drive shaft, adapted for submerging below the liquid surface, and having multiple scoops, each scoop including an upper blade portion and a lower blade portion, spaced apart at the leading edges and joined at the inner edges, and a rib extending rearward from the inner edges, each scoop being coupled to the shaft by attachment at the rib.

Abstract: An impeller assembly includes a shaft, multiple scoops spaced circumferentially about the shaft, each scoop including an upper blade portion and a lower blade portion, spaced apart at the leading edges and joined at the inner edges, and a rib extending rearward from the inner edges, each scoop being coupled to the shaft by attachment at the rib. A system and method for mixing gas or liquid into liquid include a vessel for containing liquid, a drive shaft for extending into the vessel, and an impeller assembly adapted for rotating about the drive shaft, adapted for submerging below the liquid surface, and having multiple scoops, each scoop including an upper blade portion and a lower blade portion, spaced apart at the leading edges and joined at the inner edges, and a rib extending rearward from the inner edges, each scoop being coupled to the shaft by attachment at the rib.

Abstract: A fluid seal having differing fluid levels is provided on opposite sides of a downwardly opening cup-shaped container that is longitudinally lapped by an upwardly opening annular container that is sealed to a vessel such that the lip of the cup-shaped container is submerged. The fluid seal creates a hydrostatic pressure barrier between ambient and a vessel, for example at a rotating vertical shaft. Relatively high speeds are permitted without leakage due to a number of internal horizontal and vertical baffles on one or more walls of the annular container. Barrier fluid losses due to evaporation or the like can be replaced in an embodiment wherein condensed process fluid is used as the barrier fluid, and wherein excess barrier fluid is returned to the vessel while maintaining a differential pressure barrier via the seal.

Abstract: A computer terminal including a cathode ray tube display in an explosion-protected electrically grounded enclosure. The front wall of the enclosure is formed by a hermetically sealed keypanel having an electrically conductive window located opposite the display for discharging, without sparking, static electricity to the grounded enclosure. The keypanel is formed from a rigid metal plate containing a pattern of several apertures in which the mounted pressure-sensitive piezoelectric switches which serve as data key input devices. A deformable metal sheet covers the rigid metal plate and apertures and has defined therein pressure points opposite corresponding apertures. The rigidity of the metal plate is sufficient to prevent pressure applied to one pressure point from affecting a switch at any other pressure point.