| 摘要 |
<p>A metering valve is provided having a piston assembly mounted for movement between open and close modes. The piston assembly is biased to assume a close mode. The piston assembly assumes an open mode only when a predetermined external force is applied to a valve actuating element forming a component of the metering valve. When the external force is removed, the piston assembly automatically returns to the close mode. The rate of movement of the piston assembly during a first segment of travel from the open mode to the close mode is substantially slower than the rate of movement during a second segment of the travel.</p> |
