1. Definition and Basic Function
  - Definition: A seal ring is a circular mechanical component mainly used to prevent the leakage of liquids or gases at mechanical joints.
  - Basic Function: The primary function of a seal ring is to form an effective seal in mechanical equipment, preventing the leakage of media (such as oil, water, air, etc.) and protecting internal components from external environmental influences.

2. Types and Applications
  - O-Ring: The O-ring is the most common type with a circular cross-section, suitable for both static and dynamic environments, often used in hydraulic and pneumatic systems.
  - V-Ring: V-rings have good mobility and adaptability, making them suitable for high-pressure and high-speed sealing environments.
  - U-Ring: U-rings are typically used for reciprocating motion seals, such as in hydraulic cylinders and air cylinders.
  - Y-Ring: Due to their special structure, Y-rings provide better sealing under high pressure, making them suitable for large construction machinery and aircraft engines.

3. Material Selection
  - Nitrile Rubber: Offers excellent oil resistance but is not suitable for polar solvents.
  - Silicone Rubber: Has superior high-temperature performance but is not oil-resistant.
  - Fluorocarbon Rubber: Resistant to chemical corrosion and high temperature, suitable for harsh environments.
  - Polytetrafluoroethylene: Excellent chemical stability and temperature resistance, but poor elasticity.

4. Installation and Maintenance Tips
  - Clean Installation Area: Ensure the installation surface is free of dust, oil, or other impurities.
  - Use Lubricant: Using a lubricant during installation can reduce friction and prevent damage to the sealing surfaces.
  - Regular Inspections: Regularly check for wear or damage and replace the seal ring timely to prevent leaks.

In summary, seal rings play a crucial role in modern industry. Selecting the appropriate seal ring and ensuring correct installation and maintenance can significantly enhance the reliability and efficiency of equipment.