System and method for hydraulically managing fluid pressure downstream from a main valve between set points

A method of controlling fluid pressure downstream from a main valve, comprising the steps of:

• providing a main valve having a fluid inlet and a fluid outlet, the main valve being configured to open to increase fluid flow therethrough, and close to reduce fluid flow therethrough;
• associating a variable orifice with the main valve such that the flow area of the variable orifice changes as the main valve position changes;
• generating a fluid stream having a pressure proportional to an inlet of the main valve and in fluid communication with a first chamber of a control pilot valve apparatus and a hydraulic control chamber of the main valve and an inlet of the variable orifice;
• placing an inlet of a fixed orifice in fluid communication with an outlet of the variable orifice;
• passing at least a portion of a fluid stream exiting the outlet of the variable orifice to a second chamber of the pilot valve apparatus;
• using the control pilot valve apparatus in fluid communication with the variable orifice, the fixed orifice, and the main valve to detect the pressure differential between the inlet and outlet of the fixed orifice;
• opening or closing a passageway of the first fluid chamber in response to pressure differentials between the first and second chambers of the control pilot valve apparatus;
• and
• hydraulically opening or closing the main valve in response to the detected fixed orifice pressure differential, including hydraulically opening the main valve when fluid flow through the first chamber of the control pilot valve apparatus is unimpeded, and hydraulically closing the main valve as fluid flow through the first chamber of the control pilot valve apparatus is restricted.

A method of controlling fluid pressure downstream from a main valve, comprising the steps of:

• providing a main valve having a fluid inlet and a fluid outlet, the main valve being configured to open to increase fluid flow therethrough, and close to reduce fluid flow therethrough;
• associating a variable orifice with the main valve such that the flow area of the variable orifice changes as the main valve position changes;
• passing a fluid stream, having a pressure proportional to a fluid inlet pressure of the main valve, to an inlet of the variable orifice;
• placing an inlet of a fixed orifice in fluid communication with an outlet of the variable orifice;
• using a control pilot valve apparatus in fluid communication with the variable orifice, the fixed orifice, and the main valve to detect the pressure differential between the inlet and outlet of the fixed orifice;
• hydraulically opening or closing the main valve in response to the detected fixed orifice pressure differential;
• and
• setting an upper pressure set point while selectively limiting a range of travel of a high pressure diaphragm of the pilot valve apparatus, and setting a lower pressure set point by selectively limiting a range of travel of a low pressure flexible diaphragm of the pilot valve apparatus.

A method of controlling fluid pressure downstream from a main valve, comprising the steps of:

• providing a main valve having a fluid inlet and a fluid outlet, the main valve being configured to open to increase fluid flow therethrough, and close to reduce fluid flow therethrough;
• associating a variable orifice with the main valve such that the flow area of the variable orifice changes as the main valve position changes;
• generating a fluid stream having a pressure proportional to an inlet of the main valve and in fluid communication with a first chamber of a pilot valve apparatus and a hydraulic control chamber of the main valve;
• passing a fluid stream, having a pressure proportional to a fluid inlet pressure of the main valve, to an inlet of the variable orifice;
• passing at least a portion of a fluid stream exiting the outlet of the variable orifice to a second chamber of the control pilot valve apparatus;
• opening or closing a passageway of the first fluid chamber in response to pressure differentials between the first and second chambers;
• placing a fixed orifice within a pilot control system associated with the main valve such that an inlet of the fixed orifice is in fluid communication with an outlet of the variable orifice;
• detecting a pressure differential between the inlet and an outlet of the fixed orifice;
• and
• hydraulically opening or closing the main valve in response to the detected fixed orifice pressure differential, including the steps of hydraulically opening the main valve when fluid flow through the first chamber is unimpeded, and hydraulically closing the main valve as fluid flow through the first chamber of the pilot valve apparatus is restricted;
• using the control pilot valve apparatus, in fluid communication with the variable orifice, the fixed orifice, and the main valve, to detect the pressure differential between the inlet and outlet of the fixed orifice and open or close the main valve.