Electrostatic spray coating system.

摘要

In an electrostatic spray coating apparatus (10), liquid coating material is applied to a workpart inside of a spray booth (12). Alternating flows of liquid coating material, liquid solvent and air are conducted through various internal flow passages in a conduit (14) inside the spray booth. An electronic differentiator (24) is positioned adjacent a predetermined location along the conduit (14) and energized from an electrical source disposed outside of the spray booth (12) to differentiate between liquid and gas in the internal flow passage for nonintrusively detecting when the head of liquid flow reaches the predetermined location along the internal flow passage. This is accomplished by an electromagnetic field extending into the flow passage and sensing the changes in the electromagnetic field resulting from dielectric differences between liquid and gas in the flow passage.