Density maps of W₈₀ for [Fe II] λ 5.3403 μm emission line as a function of the flux ratios: H₂ S(5) λ 6.9091 μm/[Ar II] λ 6.9853 μm (top panels), [Fe II] λ 5.3403 μm/[Ar II] λ 6.9853 μm (middle panels), and [Ar III] λ 8.9914 μm/[Ar II] λ 6.9853 μm (bottom panels). The contours are spaced at intervals of 10% in data density. Results are shown for the different subsamples, as identified in the title of each panel.