Plunger-type metering pump - has plunger seals enclosing chamber flushed by different second medium

摘要

The pump has a plunger driven at one end and handling a first medium at the other, enclosed by one or more seals. The plunger (27) is enclosed by one or more additional seals (28), while a second medium flows round it between the seals. The chamber between the seals can have inlet and outlet passages, the former connected to a feed pump for the second medium.