The ornamental design for a plenum for a pneumaticdistribution system, as shown and described.
FIG. 1 is a perspective view of a plenum for a pneumatic distribution system, showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a front elevation view thereof; and,
FIG. 7 is a back elevation view thereof.
The broken line in the figure drawings represents unclaimed environment only and forms no part of the claimed design; The das-dot broken lines in the figure drawings represent the boundaries of the claim and form no part of the claimed design.