| 摘要 |
A pump for mounting on a receptacle comprises two portions which are movable with respect to each other defining between them a variable volume pump chamber; the first part comprises a wall defining a fluid inlet passage, via which the fluid contained in the receptacle can gain entry into the pump chamber; the second part comprises a wall defining a fluid outlet passage via which the fluid contained in the pump chamber can leave. The pump comprises a membrane having a first portion disposed on the outer side of the wall defining the inlet passage, such that pressure in the pump chamber applies said portion to said wall to obstruct the inlet passage when the volume of the pump chamber is reduced, and a second portion disposed on the inner side of the wall defining the outlet passage, such that an underpressure in the pump chamber applies said portion to said wall to obstruct said outlet passage when the volume of the pump chamber increases.
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