What is the difference between piston seal and rod seal?

How Do Rod Hydraulic Rod & Piston Seals Work?

Rod and buffer seals maintain sealing contact in a sliding motion between the cylinder head and the piston rod. A rod sealing system can consist of a rod seal and a buffer seal or a rod seal only.  Rod sealing systems for heavy-duty applications typically consist of a combination of both seal types.  The buffer seal is arranged between the rod seal and the piston in the cylinder head. Rod seals determine the tolerance for the rod diameter. 

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Rod seals provide a thin lubrication film on the piston rod that lubricates themselves and the wiper seals. The lubrication film must be thin enough so that it returns to the cylinder during the return stroke.

Piston seals maintain sealing contact between the piston and the cylinder bore. Piston seals are typically classified into single-acting (pressure acting on one side only) and double-acting (pressure acting on both sides) seals.

Types of Hydraulic Rods & Piston Seals

Rod Buffer Seals

These are essential for hydraulic and pneumatic cylinders, cushioning the piston rod to prevent damage and enhance system longevity. Made from materials like polyurethane, rubber, and PTFE, they're designed for durability and compatibility with various hydraulic fluids.

Rod buffer seals protect against metal-to-metal contact, reducing wear and leakage while handling high pressures, speeds, and temperature variations. By guarding against external contaminants, rod buffer seals significantly boost cylinder reliability and performance.

T-Seals

Featuring a distinctive T-shaped profile, T-seals consist of an elastomeric seal flanked by two anti-extrusion rings, enhancing their ability to withstand high pressures without being squeezed out.

T-seals outperform traditional O-rings by providing superior stability, reduced failure risk, and compatibility with a wide range of pressures and temperatures. Their design simplifies installation and improves seal retention, making them ideal for dynamic applications where reliability and efficiency are key.

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Piston Rings Supplier

Rocket Seals is a leading seal and O-Ring specialist, supplying sealing products for all industrial applications.  For over 60 years, we have served the growing and changing needs of multiple industries, partnering with leading manufacturers to update and expand our inventory to provide products that meet your latest needs.

Contact us today to see how we can solve your sealing challenges.

Optimize the performance of your equipment: discover the keys about piston and rod seals

The main difference lies in that piston seals seal the space between the piston and the cylinder wall, while rod seals ensure the sealing between the rod and the cylinder or valve housing.

Piston Seals

• Location: The piston seal is located between the piston and the cylinder wall in an internal combustion engine or other devices that use pistons, such as certain compressors and hydraulic cylinders.
• Function: The main function of the piston seal is to seal the space between the piston and the cylinder wall to prevent gas and oil leaks during the operating cycle of the engine or device. It also helps to maintain the necessary compression within the cylinder during the different stages of the cycle.
• Materials: Piston seals are usually made of materials resistant to heat and pressure, such as steel rings, composite materials, or O-rings.

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Rod Seal

• Location: The rod seal is located on the external part of the rod, which is the moving part of a valve or hydraulic or pneumatic cylinder.
• Function: The main function of the rod seal is to ensure an effective seal between the rod and the cylinder or valve housing. This seal prevents fluid leaks and ensures smooth and controlled movement of the rod during the operation of the equipment.
• Materials: Rod seals are also made of wear-resistant materials and are suitable for the specific operating conditions. Like piston seals, materials can include O-rings, U-seals, V-seals, and packings of various materials and designs.

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Can a seal serve both the piston and the rod?

Yes, it is possible for a seal to be used for both the rod and the piston. For example, in certain hydraulic or pneumatic cylinders, seals that seal both the rod and the piston can be used. These seals are placed in different positions within the cylinder:

• On the rod: The seal is placed on the external part of the rod to ensure sealing between the rod and the cylinder housing, preventing fluid leaks and allowing smooth and controlled movement of the rod.
• On the piston: Another seal is placed on the piston, sealing the space between the piston and the inner wall of the cylinder. This seal prevents fluid leaks and helps to maintain the necessary pressure inside the cylinder during operation.

Using a seal for both purposes has practical advantages, such as greater simplicity in the design and assembly of the cylinder, as well as a potential reduction in manufacturing and maintenance costs.

At JIOrings, we offer a variety of seals that can perform both roles, making them a doubly valuable choice for your industrial needs. Discover them today!

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