Pilot hydraulic system for operating control valve

A method of delivering fluid from an inlet to only one of a first outlet and a second outlet using a pilot valve system, comprising:

• providing a pilot valve system comprising:
• a lower chamber formed from:
• a pilot body having a fluid passageway defined along a central longitudinal axis thereof, the fluid passageway connecting an inlet to a first outlet located at a lower portion of the fluid passageway and a second outlet located at an upper portion of the fluid passageway, the upper and lower portions of the fluid passageway having a substantially similar width;
• and
• a neck in the fluid passageway aligned with the inlet, the neck positioned between the upper and lower portions of the fluid passageway and having a width that is less than the width of the upper and lower portions of the fluid passageway, the width of the fluid passageway at the neck being constant along the central longitudinal axis of the pilot body;
• and
• a stem in the fluid passageway, comprising an upper section, a middle section, a lower section, and first and second intermediate sections;
• wherein the upper, middle, and lower sections are all of substantially the same width;
• wherein the first intermediate section separates the upper section from the middle section and the second intermediate section separates the lower section from the middle section;
• and
• wherein the first and second intermediate sections are of substantially the same width, the width of the first and second intermediate sections being greater than the width of the upper, middle, and lower sections;
• and
• wherein the first and second intermediate sections pass through the neck of the fluid passageway;
• and
• a first stationary seal located on internal sides of one end of the upper portion of the fluid passageway and a second stationary seal located on internal sides of one end of the lower portion of the fluid passageway, the first and second stationary seals adapted to form a substantially fluid-tight closure with the stem, wherein the neck of the fluid passageway is located between the first and second stationary seals;
• an upper chamber separated from the lower chamber by a diaphragm, the upper chamber including:
• a compression spring;
• and
• an adjusting screw for controlling the amount of force provided by the compression spring against the diaphragm;
• flowing a first fluid through the inlet at the neck of the fluid passageway;
• and
• flowing a second fluid through an opening at a bottom end of the lower chamber to control a placement of the stem within the fluid passageway and determining whether fluid flows to the first outlet at the lower portion of the fluid passageway or the second outlet at the upper portion of the fluid passageway;
• wherein the pilot valve system is adapted to deliver fluid from the inlet to one outlet while ensuring that fluid does not flow to the other outlet at the same time.