APPARATUS FOR ELECTROSTATICALLY ISOLATING AND PUMPING CONDUCTIVE COATING MATERIALS

An apparatus for transferring electrically conductive coating materials such as water-based paint from a source at grand potential to an electrostatically charged dispenser includes means for periodically interrupting the transfer of coating material so as electrically to isolate the source from the electrostatic dispenser, the interrupting means comprising a coupling device (20) having first and second coupling members (19,28) communicating with the source and the electrostatic dispensing device, respectively, the coupling members (19,28) engaging to transfer coating material from the source through the coupling device, and disengaging so as electrically to isolate the source from the electrostatic dispenser, characterised in that the coupling device (20) comprises means (254,242) for creating a suction at at least one of the coupling members (19,28) in the course of disengagement thereof, so as substantially to prevent drippage of coating material as the coupling members disengage. At least one coupling member (19,28) comprises a one-way valve (214, 236), the or each one-way valve (214, 236) being moved to a valve-open position upon engagement of the coupling members to allow coating material to flow therethrough and, on disengagement of the coupling members (19,28) being moved to a valve-closed position to prevent the flow of coating material therethrough.