| 摘要 |
The operation of a vacuum-conveying hopper feeder is controlled using pneumatic logic circuitry including a leak sensor relay providing improved control accuracy and with a sensor orifice which becomes occluded by a spring-loaded plunger when the feeder body is filled to a predetermined weight. The leak sensor relay connects through a pneumatic logic NOT element to an aspirator or pump control valve and releases the vacuum allowing the contents of the body to be dumped. Time delay elements can be included between the relay, NOT element, and control valve so as to continue the filling for a predetermined interval following occlusion of the sensor orifice and to continue the dumping for a period following unblocking of the orifice.
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