ΔE 13.6, fair: the same colour family, but not a straight swap. Dark Turquoise is a little darker, more muted, warmer than Phalanx Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Dark Turquoise is a little darker, more muted, warmer than Phalanx Blue.
The same difference applies the other way round: Phalanx Blue is a little lighter, more saturated, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Phalanx Blue on the colour wheel See Dark Turquoise on the colour wheel
All matches: Phalanx Blue equivalents · Dark Turquoise equivalents