Fluid flowing from port a to port b passes through annular slit c of the first flow-control unit and through throttling orifice d of the second unit. Piston 1 is subject at its lower end to the pressure of the fluid after first flow control, and above, at its upper end, to the pressure of the fluid after second flow control and to the action of helical spring 2. When the pressure in port a increases above a definite value, piston 1 moves upward and reduces the clear opening at c. Since the discharge through throttling orifice d continues, the pressure below piston 1 drops, piston 1 moves downward and the clear opening increases again. In this way, fluctuations in flow of the fluid passing through the flow-control valve, due to fluctuations in pressure preceding the valve, are reduced.
$3655$SHP,FC$