Piston Seals

Piston seals or piston rings, are used in hydraulic or pneumatic cylinders for fluid sealing. The seal keeps the fluid on the piston side, preventing leaks to the opposite side of the cylinder, as the system pressure pushes the piston down during a pressure cycle.

Piston seals designed for bi-directional pressure

Single-acting/uni-directional piston seal

Single-acting pistons only hold pressure on one side of the piston. The seal is required to retain pressure from that direction, which then moves the piston along the cylinder. A single acting/uni-directional piston seal will have only one sealing lip that is in contact with the cylinder wall or bore.

Double-acting/bi-directional piston seal

For applications where the fluid pressure acts on both sides of the piston, a double-acting/bi-directional piston seal is recommended to seal dynamic pressure from both sides. This seal has two separate sealing lips, one for each side of the piston head.

Double-acting pistons hold pressure on both sides of a piston without leakage and allow for maximum mechanical effort in moving the piston along the bore of a cylinder.

Piston seals, both single and double-acting, can be designed for and used with integrated or separate back-up rings and guide rings.