upper peripheral edge of the pump chamber and thereafter downwardly into the container such communication is however disrupted in the fully raised position of pump piston 14 as shown in fig1 by means of an annular valve defined by an enlarged diameter portion 52 of the piston rod exterior which seats against the downwardly and outwardly flared inner periphery of collar 19 the priming valve structure of the 39 983 patent is likewise adopted for the present pump sprayer in that a small ramp or proturberance 53 is provided on inner wall 45 of section 13 so as to engage and inwardly deflect a localized portion of peripheral wall 41 of the lower piston when such piston is at or near the lower extremity of its downward stroke a downward flow of entrapped air from pump chamber 38 is thereby permitted to flow into lower section 13 through dip tube 47 and back into the container further details of the construction of protuberance 53 and the accompanying priming feature of u s pat no 4 051 983 are omitted for the sake of brevity another embodiment of the lower piston is shown in fig5 as piston 15 39 constructed similarly as piston 15 aforedescribed except that its peripheral wall or skirt 41 39 is provided with a radially extending circumferential rib 54 on its outer surface in lieu of a radially extending end edge which constantly engages the entire circumference of the inner wall of section 13 in.