Hydrostatically adjustable valve and associated system

An adjustable flow valve comprising:

• an outer housing including an inlet, an outlet, a drainage port, and an interior area;
• a spool having an internal pressure, the spool slidably positioned within the interior area of the outer housing, the spool having first and second ends, an orifice formed within the first end, the orifice allowing fluid to flow through the spool and into the interior area of the outer housing, the spool having a first orientation with the first end is flush with the inlet to thereby prevent the flow of fluid through the outlet, and a second orientation wherein the first end of the spool is positioned at a location inward of the inlet to thereby allow the flow of fluid through the outlet;
• a sleeve within the outer housing with outlet ports that are closed when the spool is in the first orientation;
• a control device for selectively varying the internal pressure of the spool, the control device fluidly interconnected to the drainage port and the orifice, the control device selectively varying the rate at which fluid drains from the drainage port, whereby draining the fluid results in the internal pressure being reduced and in the spool attaining the second orientation.