It is possible for an engineer to design a perfectly functioning cylinder, only for it to start leaking in a matter of months due to poorly selected seal material. This is because selecting the right seal material is critical, and plant managers and engineers should be well-versed in checking if the material can stand the temperature and pressure the seal will be subjected.

Reason of Temperature Rating Comes First

Every seal used has working temperature limits and going beyond these limitations will result in the material hardening, cracking, or losing its sealing edge. NBR or Nitrile Rubber has a general purpose limits and starts to deteriorate in performance at temperatures at or above 100 °C. Polyurethane on the other hand has much better abrasion resistance and will outlast NBR even at moderate temperatures. Therefore, polyurethane is a much better choice for piston and rod seals in industrial cylinders. For use cases where initial temperatures get much higher, like the seals on the cylinders near engines, furnaces and hot presses, Viton type fluorocarbon polymers will be a much better choice due to their excellent performance at much higher temperatures and their ability to resist oil breakdown even after long use.

Sealing Under Working Pressure

Sealing piston systems involves matching seals to working pressures. Seals in an assembly need to contain pressure on one side while the other side exerts a force. Piston seals have a defined profile that requires the backup ring support to match peak operating pressure. Sealing tools such as rod seals must be dynamic due to the constant movement of rod systems under pressure. A seal that does not have adequate resistance will extrude through a clearance path, especially through systems that frequently experience pressure spikes. Although a wiper seal does not carry pressure like a seal in an assembly, if a wiper becomes damaged, it allows seal contamination to enter and contact the surface of the rod, causing scoring and ultimately reducing the life of all of the seals that follow.

Typical Seal Arrangements

Piston seals, rod seals, and wiper seals have different functions and most gland assemblies have a combination of a primary seal, buffer seal, bearing seals, and a static seal assembly. The selection of the arrangement depends on the operational pressures and the cycle of the system. Duty cycles of different systems greatly vary and it is common for mismatched selections to prematurely fail systems.

Custom Seals to Meet Your Exact Requirements

Component selection and material determination requires a supplier with an understanding of the components and their operational environments. Teutonic Engineering, based out of Coimbatore, manufactures hydraulic seals and gland and piston components, as well as cylinder elements to meet the demands of industrial applications that include hard-to-control fluids like those used in the chemical industry. Working with a specialty supplier eliminates the guesswork for buying heads when sourcing replacements for cylinders that operate under varying thermal and pressure environments.

Conclusion

Cylinder downtime is expensive, and most premature seal failures trace back to a material or pressure mismatch rather than poor workmanship. Reviewing the correct hydraulic cylinder seal types based on actual operating temperature and pressure before ordering replacements is one of the simplest ways to extend service life and avoid repeat failures.