A minimum pressure shut-off valve closes off fuel flow responsive fuel pressure being below a predefined pressure. A sleeve includes at least a first flow window and a second flow window. The second window includes a notch providing a flow area based on an axial position of a spool moveable within the sleeve.

Described are water-on-water valves for use in reverse osmosis filtration systems. The water-on-water valves are regulated by the pressure in a product line, which contains fluid from a product line of the filter module and/or the product side of a water-on-water storage tank. Exemplary valves are shuttle valves that are regulated by the pressure downstream of the product side of a reverse osmosis filter module. The valves may comprise a piston within a housing, and an end of the piston may have an enlarged diameter relative to the maximum diameter of the remainder of the piston. The body of the piston may have sections of differing diameters, where the smaller diameter sections form flow channels, or the body may a diameter that is substantially the same along its length in conjunction with gratings and flow channels.

A directional poppet valve (10) has valve pistons (16-22) arranged in a valve housing (12) for controlling a plurality of fluid connections (A, B, P, T). The positions of each valve pistons (16-22) in the valve housing (12) can be changed by at least one actuating device. The fluid connections (A, B, P, T) are connected to one another or separated from one another alternately depending on the position of the valve pistons (16-22). The valve pistons (16-22) are arranged inline along at least one axis (R), consecutively and/or at least such as to partially interengage, in the valve housing (12).

A valve assembly for receiving a fluid under pressure and comprising a plurality of valves in a single valve block. The assembly may include a plurality of check valves and including a counterbalance generating valve and a 3-way valve and including a method of use. The assembly may include an adjustable counterbalance valve, a pilot-operated check valve and a 3-way valve or combinations thereof.