| 摘要 |
The metering apparatus has a metering pump (22, 23) for feeding metered quantities of chemicals into a liquid line (3), in particular into a water line. A differential-pressure transducer (10) is set with a differential pressure between two points (11, 12), this differential pressure being proportional to the rate of flow in the liquid line (3) and to the metering counterpressure. The high- and low-pressure sides (11, 12) of the differential-pressure transducer (10) are connected to a servo control means (20) for actuating the metering pump (22, 23). The metering apparatus works without external energy and can feed large metered quantities into the system against pressure. <IMAGE>
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