The ornamental design for a detector for flowmeter, as shown and described.
FIG. 1 is a front view of a detector for flowmeter in a configuration in which the detector is fully retracted, the rear view being a mirror image;
FIG. 2 is a top view thereof in a configuration in which the detector is fully retracted;
FIG. 3 is a bottom view thereof in a configuration in which the detector is fully retracted;
FIG. 4 is a right-side view of the detector both fully retracted and fully extended, the left-side being a mirror image;
FIG. 5 is a perspective view thereof;
FIG. 6 is a front view thereof in a configuration in which the detector is fully extended, the rear view of the extended configuration being a mirror image;
FIG. 7 is a top view thereof in a configuration in which the detector is fully extended;
FIG. 8 is a bottom view thereof in a configuration in which the detector is fully extended;
FIG. 9 is a cross-sectional view thereof that is cut by a broken line 9-9 in FIG. 7; and,
FIG. 10 is a cross-sectional view thereof that is cut by a broken line 10-10 in FIG. 6.