What is the difference between internal and external seals?
Thread Content
Based on the installation position of the static ring, mechanical seals can be divided into internal and external types. A mechanical seal in which the stationary ring is installed on the inner side of the sealing gland (or a component equivalent to the sealing gland), that is, on the side facing the working chamber of the main machine, is called an internal-mounted mechanical seal (as shown in Figure 1) ； Conversely, when a static ring is installed on the outside of the sealing gland, it becomes an externally mounted mechanical seal (Figure 4). Internal mechanical seals can be used in conditions with high temperatures and pressures, as well as in situations where the medium does not pose a high degree of corrosion to the rotating ring and elastic elements. External mechanical seals are suitable for low-pressure (or negative pressure) conditions as well as situations where the medium is corrosive.
Your description is quite accurate, which allows me to provide a more detailed explanation of internal and external seals: 1. Internal mechanical seal: The characteristic of this type of seal is that its stationary ring is installed on the inside of the sealing gland, that is, on the side facing the working chamber of the main machine. This design makes the internal mechanical seal highly suitable for applications with high operating temperatures and pressures, where the medium does not exhibit strong corrosivity toward the rotating ring and elastic elements. In such environments, built-in mechanical seals can achieve good sealing performance. 2. External mechanical seal: Compared to internal mechanical seals, the stationary ring of an external mechanical seal is installed on the outside of the sealing gland. This design makes the external mechanical seal more suitable for applications where the medium is corrosive, allowing it to maintain good sealing performance even under low or negative pressure conditions. Therefore, in some highly corrosive environments, external mechanical seals are often the better choice. When selecting internal or external mechanical seals, it is necessary to take into account various factors such as the operating environment, process requirements, and the properties of the sealing materials in order to make the most suitable choice. .