Abstract: A sprayer comprising a housing (10) having an internal aperture in which a spool (12) is mounted for translational movement is disclosed. The spool has a nozzle (32) mounted to it. A cavity (30), formed in the spool, is configured to provide a passageway for directing fluid from an inlet (20) in the housing to the nozzle when the sprayer is in a spraying position. The cavity also provides a fluid passageway from the fluid inlet to a fluid outlet (21), which is also formed in the housing. The latter fluid passageway permits a reverse fluid flow through the nozzle. The direction of the reverse fluid flow is opposite to spraying flow direction. Thus, the reverse fluid flow cleans the nozzle by removing matter that clogs the nozzle. A pneumatically actuated, double-acting piston and cylinder assembly is used to move the spool between the spraying position and the cleaning position.