摘要 |
A pneumatic vibratory diaphragm pump, having a casing (12, 14) comprising an upper chamber (17) having an inlet (59) by which air can be drawn from outside the casing and a lower chamber (16) having an outlet (N) from which air can issue from the casing, an oscillatory armature (22) within the lower chamber to actuate a diaphragm (28b, 30b) of at least one diaphragm and valve assembly (28, 30) and drive means (80, 20) to cause oscillatory movement of the armature. Each diaphragm and valve assembly is arranged so as to induce air to be pumped by it from the upper chamber and to discharge air into the lower chamber whereafter the discharged air is issued from said outlet. Venting means (70, 74, 76) is provided to allow air which has been discharged from the casing into a container to return therefrom and exhaust from the casing when the pump is inactive. |