Backpressure regulator with easy pump start-up

A fluid control system for providing start-up and overpressure relief functions to a primary fluid carrier, the system comprising:

• a main valve having an inlet, an outlet, a gallery disposed between the inlet and the outlet, a valve seat fixedly disposed in the gallery, and a valve plug slidably disposed in the gallery between a closed position engaging the valve seat and an open position spaced away from the valve seat, the valve plug being biased toward the closed position via a control spring;
• a start-up pilot device and an overpressure pilot device, each of the start-up and overpressure pilot devices including a valve body and a control assembly including a diaphragm having opposite first and second surfaces and operably coupled to a valve plug, the valve body including an inlet port, an outlet port, and a valve port disposed between the inlet port and the outlet port, the valve plug movable between a closed position engaging the valve port and an open position spaced away from the valve port,
• wherein the valve plug of the start-up pilot device is biased toward the open position by a start-up control force applied to the first surface of the diaphragm of the start-up pilot device, and the valve plug of the overpressure pilot device is biased toward the closed position by an overpressure control force applied to the first surface of the diaphragm of the overpressure pilot device;
• a first supply line providing fluid communication between the inlet of the main valve, the inlet port of the start-up pilot device, and the gallery of the main valve;
• a first exhaust line providing fluid communication away from the outlet port of the start-up pilot device to a first target destination;
• a first sensing line providing fluid communication between the second surface of the diaphragm of the start-up pilot device and a first registration source;
• a second sensing line providing fluid communication between the second surface of the diaphragm of the overpressure pilot device and a second registration source, wherein at least one of the first and second registration sources includes the inlet of the main valve;
• a second exhaust line providing fluid communication between the outlet port of the overpressure pilot device and a second target destination;
• and
• a second supply line providing fluid communication between the inlet port of the overpressure pilot device and the gallery of the main valve.

A method of providing start-up and overpressure relief functions to a primary fluid carrier using a fluid flow control system that includes a main valve, a start-up pilot device fluidly connected to the main valve, and an overpressure pilot device fluidly connected to the main valve, the method comprising:

• exhausting fluid from an inlet of the main valve to the outlet of the main valve through the start-up pilot device via a first supply line extending from the inlet of the main valve to an inlet port of the start-up pilot device and a first exhaust line extending from an outlet port of the start-up pilot device to an outlet of the main valve;
• automatically closing the start-up pilot device when a start-up closing pressure sensed by a diaphragm of the start-up pilot device is greater than or equal to a control pressure of the start-up pilot device;
• automatically opening the overpressure pilot device when a relief opening pressure sensed by a diaphragm of the overpressure pilot device is greater than or equal to a control pressure of the overpressure pilot device;
• and
• exhausting fluid from a gallery of the main valve to the outlet of the main valve while the overpressure pilot device is open via a second supply line extending from the gallery of the main valve to an inlet port of the overpressure pilot device and a second exhaust line extending from an outlet port of the overpressure pilot device to the outlet of the main valve.

A method of providing start-up and overpressure relief functions to a primary fluid carrier using a fluid flow control system that includes a main valve, a start-up pilot device fluidly connected to the main valve, and an overpressure pilot device fluidly connected to the main valve, the method comprising:

• exhausting fluid from an inlet of the main valve to a first target destination through the start-up pilot device via a first supply line extending from the inlet of the main valve to an inlet port of the start-up pilot device and a first exhaust line extending from an outlet port of the start-up pilot device to the first target destination;
• automatically closing the start-up pilot device when a pressure at the inlet port of the start-up pilot device is greater than or equal to a control pressure of the start-up pilot device;
• automatically opening the overpressure pilot device when a pressure at the inlet of the main valve is greater than or equal to a control pressure of the overpressure pilot device;
• and
• exhausting fluid from a gallery of the main valve to a second target destination through the opened overpressure pilot device via a second supply line extending from the gallery of the main valve to an inlet port of the overpressure pilot device and a second exhaust line extending from an outlet port of the overpressure pilot device to the second target destination.