Gas control unit for a burner
First Claim
1. A gas control device for controlling the flow of gas to a burner, which comprises:
- a first, upstream main valve and a second, downstream main valve arranged in spaced and series relation to the gas flow path through the device for movement together between open positions in which they allow for gas flow through the device and a closed position in which they close the flow path and segregate a first chamber within the gas flow path, a second chamber which is closed when the main valves are open but which is communicable with the first chamber through a passage controllable by an auxiliary valve arranged to open when the main valves are closed and close when the main valves are opened, and a shut-off valve which is normally open but which is responsive to the gas pressure within the second chamber so as on leakage of gas past the first main valve when in the closed position, to close an orifice forming part of the gas flow path and, by virtue of closure of the second chamber by the auxiliary valve closing said passage, to maintain the gas flow path closed when the main valves are subsequently opened.
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Accused Products
Abstract
A gas control device for controlling the gas supply to the burner of a domestic hot water boiler has two main valves arranged in series in the gas flow path so as when closed to define a chamber between them. A second chamber is communicable with this chamber through an auxiliary valve which is open when the main valves are closed and closed when the main valves are open. A shut-off valve is responsive to the pressure in the second chamber so as to close the flow path if gas leaks through the upstream main valve when supposedly closed. The subsequent closing of the auxiliary valve when the main valves are later opened maintains the pressure in the second chamber so that the shut-off valve remains closed.
26 Citations
11 Claims
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1. A gas control device for controlling the flow of gas to a burner, which comprises:
a first, upstream main valve and a second, downstream main valve arranged in spaced and series relation to the gas flow path through the device for movement together between open positions in which they allow for gas flow through the device and a closed position in which they close the flow path and segregate a first chamber within the gas flow path, a second chamber which is closed when the main valves are open but which is communicable with the first chamber through a passage controllable by an auxiliary valve arranged to open when the main valves are closed and close when the main valves are opened, and a shut-off valve which is normally open but which is responsive to the gas pressure within the second chamber so as on leakage of gas past the first main valve when in the closed position, to close an orifice forming part of the gas flow path and, by virtue of closure of the second chamber by the auxiliary valve closing said passage, to maintain the gas flow path closed when the main valves are subsequently opened. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
Specification