| 摘要 |
An improved slow opening gas valve providing for continuous gradual and smooth opening of the gas valve includes an expansible auxiliary chamber connected to an expansible control chamber by a metering orifice. The expansible auxiliary chamber slows expansion of the expansible control chamber, thereby slowing opening of the gas valve and allowing gas to ignite at a lower pressure with a much less audible sound. The gas valve is provided with a normally closed valve member for controlling flow of gas through the gas valve and a diaphragm forms a movable wall of the expansible control chamber that is operable upon expansion of the chamber to move the valve member to an open position. The expansible auxiliary chamber also comprises a movable diaphragm to control the opening of the gas valve and provide gas flow gradually and smoothly. In an alternate embodiment, a gas valve is configured to provide an initial gas flow through a bypass orifice in the closed valve member, which enables ignition of the gas at an optimum gas pressure instantly, followed by a gradual and smooth opening of the valve member. This arrangement provides a "step" function followed by the desired slow opening of the valve member.
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