| 摘要 |
<p>A jet type liquid level sensor and its combination with a fluid pressure operated valve whose opening and closing is controlled by the sensor at predetermined liquid levels within a tank in which the sensor and valve are installed. The sensor is designed for installation such that the jet stream issuing from a nozzle thereon travels horizontally to a receiving orifice which transmits the velocity head of the jet stream to an actuator for holding the valve open until such time that the jet stream is diffused by rising level of liquid in the tank. The nozzle has a shroud surrounding the jet stream and a pickup tube that extends a substantial distance below the nozzle. The pickup tube delivers liquid to the shroud for diffusing the jet stream when the liquid level is falling from the predetermined high shutoff level to the predetermined low reopening level corresponding to the position of the lower end of the tube at which point the jet stream is re-established for opening the valve. The high and low levels are a substantial distance apart so as to avoid frequent cycling of the valve.</p> |
