Piston Seals

Piston seals are dynamic seals, typically single-acting (pressure acting on one side only) and double-acting (pressure acting on both sides) seals. The choice of piston seal is determined by the way in which the cylinder operates.

Single-Acting Pistons

Single-acting pistons only contain 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.

Double-Acting Pistons

Double-acting pistons contain pressure on both sides of a piston without leakage. They allow maximum mechanical effort to the moving the piston along the bore of a cylinder.

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.

UK Seals supply a wide range of piston seals including; PTFE seals, U Seals, fabric seals, compact seals, cup seals and V packs. We supply Compact seals/3/5 Part Piston Seals and V packs (chevron) in many sizes and profiles. Contact UK Seals for additional available profiles. Again, non-standard sizes are our strength.