| 摘要 |
<p>An electrostatic powder coating system for selectively spraying any one of a plurality of different pulverant powder materials from a common spray gun without the necessity for physically disconnecting or reconnecting the spray source of the different pulverant materials to the common gun. This system includes the common spray gun, a plurality of powder material reservoirs and associated venturi pumps connected to a common manifold block. That manifold block is also connected to a source of purging air flow. Internally of the manifold block there are pinch valves operable to selectively connect and disconnect each of the different powder material reservoirs and the purging air flow to the common spray gun. Additional pinch valves separate the material reservoirs from the venturi pumps associated with each reservoir. The various pinch valves, purging air and pump air flows are sequenced such that changes from one powder to another are effected in a very short time duration without the contamination of any new powder with any residual powder from a previous cycle and without the occurrence of any puffing or unusually heavy flows of powder at the beginning or end of a spray cycle.</p> |
