| 摘要 |
<p>INVENTION OF: JOHN L. FOLLETT FOR: AUTOMATIC SHUT-OFF VALVE AND METHOD OF OPERATION THEREOF A valve having a closure element in the form of a tapered plug normally maintained by gravity on a vertical rod extending loosely into a bore in the plug. Flow of fluid through the valve in excess of a predetermined rate acts on a flowresponsive surface of the plug to move the latter into engagement with a valve seat, thus blocking further flow. The construction is particularly suited to close control of the flow rate at which closure of the valve occurs. The size, shape, weight and position of various elements influences the magnitude of the flow rate required for closure and may be tailored to effect closure repeatedly at a virtually exact desired flow rate. One embodiment includes means for selectively changing the shape of the flow-responsive surface, and thereby the flow rate at which closure occurs. In the preferred embodiment, the closure element is retained in the closed position by a permanent magnet until intentionally reset by external means, such as the application of a back pressure from the downstream side of the closure element sufficient to overcome the magnetic attraction, The invention also resides in the method of operating the preferred embodiment of the valve by effecting reset with application of back pressure from external means.</p> |
