A system for purging fluid delivery systems such as paint spray guns with non-toxic, non-polluting cleaning solvents. A sealed tank is provided for storing a cleaning solvent with air pressure applied to deliver the cleaning solvent through a coaxial hose to a slide selectable valve. Pressurized air is also connected to one of the conduits of the coaxial hose. Spray guns or fluid delivery systems are cleaned and purged by first releasing the cleaning solvent in the passageways and then quickly switching to a blow-down mode on the slide selectable valve to discharge the cleaning solvent from the spray gun passages.