We claim the ornament design for a pressure detector, as shown and described.
FIG. 1 is a front view;
FIG. 2 is a right side view;
FIG. 3 is a plane view;
FIG. 4 is a bottom view; and,
FIG. 5 is a perspective view.
The article is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.