The choice of piston seal is decided by the way in which the cylinder operates. For a cylinder which is exclusively single-acting, capable of sealing dynamic pressure from one side (unidirectional), it is always best to choose the type of seal designed to provide optimum sealing qualities for single-acting functions.

The best sealing capacity of a double-acting cylinder, capable of sealing dynamic pressure from both sides (bidirectional), is achieved by choosing a double-acting seal.

A piston design where two single-acting seals on the piston for a double-acting cylinder are used can easily give rise to a breakdown. The reason is that a very high pressure can be trapped between the seals.

Piston seals, both single- and double-acting, can be designed for and used with integrated or separate back-up rings and guide rings.
Hallite offers a wide range of piston seals that provide the ultimate in leakage control. Piston seals are usually manufactured in our high performance polyurethane Hythane® 181, Hallprene® rubber/fabric composite or polyester elastomer.