| 摘要 |
<p>An improved check valve is disclosed for use in a system for sequentially delivering primary and secondary solutions through a common conduit. The check valve comprises a hollow housing with an inlet and an outlet connected to an enlarged intermediate portion. Sealed at its periphery in the enlarged portion is a flexible diaphragm characterized by having foraminous means in at least its outer portion and imperforate means in its central portion. The imperforate means is spaced from a valve seat surrounding the passage at the inner end of the inlet so that when the primary solution flows from the inlet to the outlet, it will pass freely around the imperforate means and through the foraminous means. When an increase in pressure, even though slight, is exerted against the diaphragm caused by flow of the secondary solution in the direction of the outlet to the inlet, the diaphragm moves towards the inlet causing the imperforate means to seal against the valve seat and stop the flow of the primary solution.</p> |
