Method and apparatus for flow diversion in a high pressure fluid delivery system

A method of operating a fluid delivery system for the transfer of fluid under relatively high pressure from a supply through conduit means and out a closable discharge, wherein said fluid delivery system employs between the supply and discharge a bypass valve for diverting the flow away from the discharge under substantially reduced pressure when the discharge is closed, the bypass valve having a bypass port and a piston movable between a bypass port blocking position when the discharge is open and a bypass port open position when the discharge is closed, the piston having two generally parallel working surfaces of different areas and a passage through the length of the piston, the method comprising the steps of:

• opening the discharge;
• flowing the fluid over the smaller of the working surfaces in a direction generally parallel to the plane defined by the smaller working surface and therewith the piston is generally responsive only to the static pressure of the flowing fluid;
• communicating the flowing fluid with the larger of said working surfaces, whereby the piston is held in the bypass port blocking position;
• closing the discharge;
• obstructing fluid communication between the larger working surface and the flowing fluid;
• and
• passing fluid from the larger of the working surfaces through the passage and out the bypass port, whereby the piston moves to the bypass port open position and fluid is diverted out the bypass port at a substantially reduced pressure.

For use in a fluid delivery system wherein fluid is transported under pressure from a supply to a closable discharge, an apparatus for diverting the flow to a drain under substantially reduced pressure when the discharge is closed, the apparatus comprising:

• a housing having a central cavity, an inlet for connecting said cavity to said fluid supply, an outlet for connecting said cavity to said discharge, and a bypass port for connecting said cavity to said drain;
• blocking means within said cavity moving from a bypass port closed position when said discharge is open to a bypass port open position when said discharge is closed, said blocking means comprising a shaft having a sealing means at one end and at least two working surfaces of different areas proximate the other end;
• means for providing fluid communication between said working surfaces;
• means for interrupting fluid communication between said working surfaces;
• and
• means for reducing fluid pressure on the larger of said working surfaces, whereby said blocking means moves to the bypass port open position and flow is diverted at substantially reduced pressure.

A bypass valve for a pressurized fluid delivery system of the type in which fluid is transported from a fluid supply through conduit means to a closable discharge, the bypass valve being located in said fluid delivery system between the supply and discharge, said bypass valve comprising:

• a housing having a central cavity, an inlet, an outlet, a bypass port between said inlet and outlet, and a channel providing fluid communication between two portions of said cavity;
• a piston within said cavity movable between a bypass port closed position when said discharge is open and a bypass port open position when said discharge is closed, said piston comprising a shaft having a bypass port sealing means at one end, a first working surface at the other end, a second working surface having an area less than said first working surface and located between said ends, and a passage through the length of said shaft for passing fluid from said first working surface through said bypass port, said working surfaces of said piston generally separating said two portions of said cavity from one another;
• and
• means responsive to the dynamic pressure of the flowing fluid for obstructing said channel when said discharge is closed, whereby fluid passes from said first working surface through said passage and said bypass port, said movable blocking means moves to the bypass port open position, and fluid is diverted through said bypass port at a substantially reduced pressure.

For use in a pressurized fluid delivery system employing a pump and a closable discharge an apparatus for regulating the fluid pressure when the discharge is open, and for diverting the flow of fluid out of the system at a substantially reduced pressure when the discharge is closed, the apparatus comprising in combination:

• a bypass valve, said valve comprising a housing having a central cavity, an inlet, an outlet, a bypass port between said inlet and outlet for the diversion of fluid out of the fluid delivery system, and a channel for providing fluid communication between at least two portions of said cavity;
• a piston within said cavity for blocking said bypass port and movable from a bypass port closed position when the discharge is open to a bypass port open position when the discharge is closed, said piston having a passage throughout its length and at least two generally parallel working surfaces of different areas, said working surfaces generally dividing said cavity into said two portions;
• and means responsive to the dynamic pressure of the flowing fluid for obstructing said channel, said obstructing means comprising a slidable seal and resilient means for urging said slidable seal against said channel when the discharge is closed, whereby fluid from the larger working surface passes through said passage and said bypass port, said piston moves to the bypass port open position, and fluid is diverted through said bypass port at a substantially reduced pressure;
• a pressure regulator connected to said bypass valve proximate said bypass port for regulating the pressure within predetermined pressure limits when said discharge is open;
• and
• means for directing fluid from said bypass valve to said pressure regulator when said discharge is open and said blocking means is in the bypass port closed position.