Tank for Backpack Sprayer

FIG. 1 is a front perspective view of a tank for backpack sprayer showing the new design; FIG. 2 is a front thereof; FIG. 3 is a rear view; FIG. 4 is a right side view; FIG. 5 is a left side view; FIG. 6 is a top view; FIG. 7 is a bottom view; and, FIG. 8 is a rear perspective view. The broken lines shown in the drawings are for the purpose of illustrating portions of the article and form no part of the claimed design.