| 摘要 |
Check valves for positive displacement pumps with an extended capacity to sealingly enshroud granules, and check vent valves with capacity to capture a quantity of fluid during a pump delivery stroke, and return that quantity of fluid to flush the inlet parts of a vent system during a pump induction stroke are described. The capacity of a check valve to capture and return a quantity of fluid is provided by a flexible tube type check valve having a flexible tube reservoir between a first valve part and a second valve part wherein the flexible tube reservoir captures fluid while the check valve is opening, and expels that fluid to flush the inlet parts of the vent system while the check valve is closing. The figure shows a flexible tube check valve (30) with a longer section of flexible tube (110) between a first flexible tube valve (102a, 102b), reinforced against external pressure, and a second flexible tube valve (101a). Ghost outlines (110D) and (110C) illustrate the progressive closing of the longer section of the flexible tube, during which fluid is expelled through the valve inlet (13E).
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