Abstract: An improved pump for fluid is characterized by one or more turbine pumping stages each having outlet ports configured to provide a constant fluid pressure from the pump for various flow rates of the fluid. The stages are connectable in series so that each increases the pressure of the pumped fluid by a predetermined amount, and each includes a housing having a pumping chamber with an inlet thereto and outlet ports therefrom, and an impeller rotatable in the chamber to move ends of blades thereof past the ports. The ports are uniquely configured to have fluid flow areas which increase with increasing distance from the chamber, whereby the pressure of the pumped fluid remains substantially constant for all flow rates of the fluid up to a design flow rate, and a fluid bypass port of adjustable flow area is provided in at least one of the pumping stages for controlling the pressure of the fluid at an outlet from the pump.

Abstract: A fluid-containing mattress for reducing rapid fluid motion in the mattress is provided in one direction while permitting fluid flow in the opposite direction. The mattress comprises upper and lower sheets connected together in superposed relation. A number of thin, elongated members or strips are internally attached to the upper and lower sheets within the mattress. A strip attached to the upper sheet and a strip attached to the lower sheet are intermittently joined together at their longitudinal edge portions to form a one-way strip valve. A plurality of these strip valves are formed within the mattress to selectively direct fluid motion. Passages are also provided to bypass these strip valves so that the fluid eventually returns to all segments of the mattress and a uniform displacement of fluid is maintained in the mattress.