| 摘要 |
A combination shut off and check valve is disclosed in which the shut off valve function is provided by a manipulable ball closure. A loose ball is contained in a chamber upstream of the ball closure. A seat for the loose ball is provided at the downstream end of this chamber and is located either on the ball closure or on the downstream opening of the chamber. The loose ball will not seat itself ordinarily because the chamber is sufficiently large so as to cause the center of the loose ball to be below the central axis of the ball closure flow hole. A pressure differential in the downstream direction causes the loose ball to roll up an inclined ramp leading to the seat, where it seats in check valve fashion.
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