| 摘要 |
<p>A two-stage float actuated shut-off valve for use in underground fuel storage tanks utilizes a drop tube coaxially mounted within the storage tank fill pipe. Fuel flowing into the tank is passed through the drop tube which projects downwardly into the interior of the tank to a valve housing located at the lower end of the drop tube. Floats slidably mounted in a recessed area in the housing outside of the drop tube within the tank independently operate pivoted valve doors to a closed position within the valve housing, a lower float closing one valve door to block a major portion of incoming fuel flow passage when the level of fuel in the storage tank reaches a predetermined first level and a second upper float causing the secondary valve door to overlap an aperture in the main valve door to almost completely close the flow of fuel to the tank.</p> |
