I claim the ornamental design for an injection site for medical fluid lines, as shown and described.
FIG. 1 is a front perspective view of the injection site for medical fluid lines comprising the new design;
FIG. 2 is a front elevation view thereof, the rear elevation view being identical thereto;
FIG. 3 is a left side elevation view thereof, the right side elevation view being identical thereto;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a rear perspective view thereof.
The dash dot lines immediately adjacent to the claimed area in FIG. 4 represent the boundaries of the claimed design. The dashed lines in the figures illustrate the portions of the design that form no part of the claimed design. None of the broken lines form any part of the claimed design.