A device for supplying a sprayer with a liquid coating comprises a one valve having a moving needle, a valve body defining a circulation volume for the coating and a seat for supporting the needle. A pneumatic drive for translating the needle along an axis away from or towards the seat comprises a piston constrained to move with the needle and sliding within a guide body. A head and the guide body define a variable volume chamber. The head is constrained to rotate with the volume via slots on the head and corresponding protruding elements on the guide body. The guide body is screwed onto the valve body along the axis. The head includes driving reliefs for rotation of the head around the axis for screwing onto the valve body. A tool for mounting/dismounting the device comprises a maneuvering handle and an end-piece having reliefs complementary to the driving reliefs.
