| 摘要 |
A system for the metered pumping and dispensing of fluid includes a filter for the pumped fluid and a pump connected to the filter. The pump is of the displacement type which includes a tubular, longitudinally-contractable bellows to receive fluid for pumping, fluid-activated reciprocating means to expand and contract the bellows, and means to selectively introduce working fluid to the reciprocating means. A rigid fluid-tight chamber is formed to surround the bellows, and means are provided to selectively introduce working fluid into chamber, whereby the working fluid assists in contracting the bellows as well as in partially balancing the internal pressure on the bellows.
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