Piston Cups are normally employed in moderate pressure cylinders up to 1500 P.S.I. A primary advantage is the ability to accommodate broad cylinder diameter tolerances as shown in Figure 1. Series No. 17 – Piston Cups have knife trimmed sealing lips to eliminate all molding flash and to provide maximum sealing performance at low pressure.
In order to establish proper sealing interference on the piston cups, the piston should be machined to the “L” dimension as shown in Figure 2, Page 2.
Standard sizes of piston cups are listed on page 2 of this technical bulletin. The I.D. dimension shown is standard, however, larger or smaller diameters can be provided to accommodate existing designs.