Hydraulic cylinders are essential components in all hydraulic systems, and as they contain fluid to create the push and pull force of a hydraulic system they require seals.
Hydraulic seals are found in most hydraulic cylinders and are relatively soft, non-metallic rings. These seals are gasket-like rings designed to seal areas between the components in the cylinder to ensure that there is no leakage of the hydraulic fluid. The seals are designed to fit the components in a hydraulic cylinder while creating a leak-proof seal around them. These rings can be fixed in a group of seals which form a sealing assembly to block or separate fluid in reciprocating motion applications.
These seals are o-rings that feature a groove within the lip for them to fit securely with the components. This groove moves over the component to ensure that no leakage occurs, even when the cylinder’s piston moves, and the fluid is pressurized.
Hydraulic seals are made from different materials such as polyurethane, rubber or PTFE. Depending on what application it is needed for, this will decide the type of material needed due to fluid type, pressure, fluid chemical compatibility and temperature. Rubber seals are the most common as they are elastic, resistant to cracking and are long-lasting. Polyurethane seals are similar to rubber in sealing properties but are much stronger and are more resistant against wear and tear. Although not as common as rubber and polyurethane, PTFE seals are strong, flexible and resistant to extreme temperature.
Hydraulic seals can found as either dynamic or static seals. Static seals don’t move and are mostly found in a groove which allows it to seal only within a confined space, providing the same properties as a gasket. For this seal to work the seal needs to be under pressure. A dynamic seal experiences movement. A rod seal is a type of dynamic seal that moves on its outer diameter along the shaft of the hydraulic cylinder, while a piston seal is a type of dynamic seal that moves on its outer diameter along the tube or bore of the hydraulic cylinder.
To understand which seals are best suited for your hydraulic system, Power Team SA, suppliers of quality hydraulic components and accessories, are on hand to help. With decades of experience within the hydraulic industry and with locations throughout South Africa and parts of southern Africa, Power Team SA is available to provide you with an expert solution.