An O-ring seal is a type of mechanical seal that consists of a circular elastomeric ring that fits into a groove and compresses between two mating surfaces to create a tight barrier. O-ring seals are widely used in various applications, such as hydraulic and pneumatic systems, valves, pumps, cylinders, and connectors, because they are simple, versatile, and cost-effective. However, O-ring seals also have some limitations of use that need to be considered before selecting them for a specific purpose. Some of these limitations are:

- O-ring seals are sensitive to temperature changes and may lose their elasticity or degrade if exposed to extreme heat or cold.

- O-ring seals are susceptible to chemical attack and may swell, shrink, or crack if exposed to incompatible fluids or gases.

- O-ring seals are prone to extrusion and abrasion if the groove dimensions are not properly designed or if the pressure is too high or fluctuating.

- O-ring seals are subject to installation damage and may twist, stretch, or cut if not handled carefully or lubricated adequately.

Therefore, O-ring seals are not suitable for every application and require careful selection of the material, size, shape, and hardness of the ring, as well as the design of the groove and the mating surfaces. By following the appropriate guidelines and standards, O-ring seals can provide reliable and effective sealing performance for a long time.