Abstract: A liquid sprayer apparatus of the type in which liquid is caused to flow from a liquid supply tank, through a spray conduit, to a spray nozzle assembly. The spray nozzle assembly comprises: an adapter mounted to the spray conduit; and a spray nozzle holder; and a spray nozzle configured to produce a flat fan spray pattern. The nozzle is received in the nozzle holder, and the holder is coupled to the adapter such that the nozzle adjoins the adapter in a secure assembly. A self orienting indexing system, associated with the adapter and the nozzle, orients the nozzle in either one of two orthogonal bearing positions relative to the adapter upon the coupling of the holder to the adapter. The self orienting system includes a plurality of indexing holes contained in the adapter and a plurality of matching indexing spurs projecting from the nozzle.