| 主权项 |
1. An automatic flow control system for use with a main valve apparatus comprising a body having an inlet for coupling to a first end of a water pipe and an outlet for coupling to a second end of a water pipe, a main valve member disposed between the inlet and the outlet and moveable between a closed position in which flow of water through the main valve apparatus is inhibited and an open position to facilitate flow of water through the main valve apparatus, a main valve operator comprising a diaphragm or piston cooperating with the main valve member and the main valve body to provide a control chamber, the main valve operator responsive to control pressure in the control chamber to move the main valve member between the closed position and the open position, and a restriction mechansim disposed between the first end of the water pipe and the second end of the water pipe for creating a pressure differential, the automatic flow control system comprising:
a junction including an inlet port for fluid communication with the inlet of the main valve apparatus by an inlet conduit, a control port for fluid communication with a control chamber of the main valve apparatus by a control conduit, and a pilot port; a pilot valve assembly comprising:
a differential pilot valve apparatus including a differential valve inlet coupled to the pilot port of the junction, a differential valve outlet, and a differential valve member disposed between the differential valve inlet and the differential valve outlet, the differential pilot valve apparatus responsive to the pressure differential to move the differential valve member between an open position in which water flows from the differential valve inlet to the differential valve outlet and a closed position in which water flow from the differential valve inlet to the differential valve outlet is inhibited;a first pilot valve apparatus including a first pilot valve inlet coupled to the differential valve outlet, a first pilot valve outlet, and a first pilot valve member disposed between the first pilot valve inlet and the first pilot valve outlet, the first pilot valve outlet coupled to the second end of the water pipe to facilitate flow of water from the differential valve outlet, through the first pilot valve apparatus, to the second end of the water pipe when the differential valve member is in an open position, the first pilot valve apparatus being responsive to a first pressure to close the first pilot valve member to reduce flow of water through the first pilot valve apparatus;a second pilot valve apparatus including a second pilot valve inlet coupled to the junction, a second pilot valve outlet, and a second pilot valve member, the second pilot valve outlet coupled to the second end of the water pipe to facilitate flow of water from the junction, through the second pilot valve apparatus, to the second end of the water pipe when the second differential valve member is in an open position, the second pilot valve apparatus being responsive to a second pressure to close the second pilot valve member to reduce flow of water through the first pilot valve apparatus,wherein the first pressure differs from the second pressure. |
