The design of seals must take into consideration the qualities of their materials and the pressure which occurs in operation. However, a number of principles dictate the design of seals. Earlier lip seals were U-rings or cup seals made from leather. Diverse seal designs became possible with the development of artiﬁ cial elastomer and productionof molds.
Customized seals to solve speciﬁ c problems could be produced. It is not easy for the designer to select seals that are most appropriate for rods and pistons as a number of factors to be considered are often overlooked. The follcwing selection criteria must be adhered to when selecting seals. Seals must be installed correctly in order to achieve best performance. If not, the required functions will not be performed and the lifespan will be reduced. The following rules must be adhered to in order to avoid issues.