The system has a precompression valve movable between a position closing off the connection in which it abuts a seat on the mouth of the conduit, and a position releasing the connection in which it is spaced from the seat. The precompression valve is biased to the closing position by a spring. The space is connected to a pump and the conduit is connected to the discharge nozzle. An Independent claim is included for a spraying device using the above precompression system.
