Abstract: A method and arrangement for maintaining fluid flow pressure in a system at a preset, almost constant level. A method for maintaining fluid flow pressure almost constant regardless of mass flow. The arrangement including a pressure accumulator, and a nozzle valve. The nozzle valve having a valve body and axially oriented needle for opening and closing the mouth of its outflow channel. The needle shaft guided by a slide element mounted inside the valve body. The inflow into the flow body passes to the other side of the slide element through one or several channels. The needle moves axially to open and close the channel because of the forces acting upon it. Forces acting upon it may include the accumulator, the inflow and a spring. The needle's movement adjust the cross-sectional area of the outflow channel mouth not disposed by the needle head to maintain an almost constant pressure.

Abstract: A method and arrangement for maintaining fluid flow pressure in a system at a preset, almost constant level. One application is an impulse turbine's nozzle valve, which automatically maintains the system pressure essentially constant so that it does not depend on occasional variation of the pumped inflow, resulting that also the jet from the nozzle remains constant and its kinetic energy optimal. The nozzles independently maintain system pressure when the inflow varies.