Abstract: A flow control valve includes a piston moveable in a cylindrical chamber between an inlet opening and an outlet opening. The piston head has a maximum diameter smaller than the wall of the chamber to define a fixed orifice. The opposite end of the piston has a sleeve which partially blocks the outlet opening depending upon the position of the piston in the chamber which in turn depends upon the pressure differential across the fixed orifice.

Abstract: A fluid flow control valve having a plug opening with a plug having a central passage for discharging fluid from the controller. The plug opening has a smaller cylindrical guide surface, threaded for engaging the plug, and a larger cylindrical guide surface. The plug has similarly shaped surfaces for engaging the guide surfaces of the plug opening to precisely locate the plug with respect to an impeller chamber.

Abstract: A ratio mixing valve for mixing first and second fluids in a constant volumetric ratio regardless of variations of supply pressures of the two fluids. The valve has an inlet passage for the first fluid that passes through a spool valve chamber, and an inlet passage for the second fluid that also passes through the spool valve chamber. Vent passages connect the two fluid passages to the ends of the spool valve chamber. The spool valve has a pair of annular grooves aligned with the two inlet passages. One groove partially blocks one of the inlet passages to form a variable orifice that responds to pressure changes in the incoming fluids by moving the spool valve to a position which adjusts the volumetric flow through the two passages to maintain a constant ratio between the fluids in the mixture.