Spray gun conversion adapter, spray gun and conversion process

Adapter 2 for converting a hand-triggered paint spray gun to be automatically triggerable. The spray gun comprises a gun body 180 having a nozzle (80; fig. 11) for spraying liquid paint, an air duct (85/87; figs. 4, 11) for conducting pressurized air towards the nozzle for atomization, and a counter surface (e.g. 390; figs. 5-6) for sealing the air duct. The adapter 2 comprises: connecting means 200 for attaching the adapter to the gun body 180; an (e.g. electrical or compressed air) energy supply connector 210, 220; a poppet 301 (valve) comprising a sealing surface (e.g. frustoconical or hemispherical 370; fig. 5-6, 9); and a poppet actuator 230 to automatically move the poppet between sealed position (fig. 6) and open position (fig. 5). With the adapter attached to the gun, in the open position compressed air is allowed to enter the duct, whereas in the sealed position the poppet sealing surface contacts the counter surface to block airflow. The adaptor may be inserted into gun body space 400 previously occupied by a control knob (60; fig. 1), spring and needle (20; fig. 2); with the adaptor including a replacement needle 21, movement of which controls amount of paint flow.