| 摘要 |
PURPOSE:To allow a valve to be installed in a gas passage with a small diameter by forming a valve seat in a gas passage and providing a supporting portion of a ball valve directly below a valve port. CONSTITUTION:Under a normal gas usage condition, a ball valve 21 is stationarly supported on a valve receiving member 20; the gas flowing from a gas pipe connection port 11a passes through a gas passage 18a, a gas path 24, and a gas passage 17 in a shutter 12; then it flows into a gas passage 18b. On the other hand, when an abnormal condition occurs, the gas passage 18b is decompressed due to a decrease of resistance at the gas consumption side; a pressure difference is generated between upper and lower portions near the valve port 19a of a valve seat 19; and at the same time a pressure difference is also generated between it and the center portion directly below the valve port 19a by the gas stream quickly flowing into the valve port 19a through the annular gas path 24; the ball valve 21 is absorbed and guided to the decompressed side, i.e., upward, by these pressure differences; and it is coupled with the valve seat 19 in close contact by pressure to cut off the gas stream. Since the ball valve is supported by a supporting portion provided directly below the valve seat, the diameter of the supporting portion is not required to be made large with respect to that of the ball valve, and its height can be made low, thus the whole body can be easily made small- sized. |
