What are the different types of mechanical seals?

For pot seals, a dual-seal arrangement with the seals back to back is generally used; for flushing, the 53C or 54 schemes are commonly employed, and corresponding bearings are selected based on the equipment.

I. Classification of mechanical seals: Based on whether the spring element rotates or remains stationary, they can be divided into rotary internal-flow unbalanced single-face seals, abbreviated as rotary types； Stationary external-mounted internal-flow balanced single-face seal, abbreviated as stationary type. Based on whether the static ring is located inside or outside the sealing end face, they can be divided into internal-type and external-type. Based on the leakage direction of the sealing medium, they can be divided into internal leakage and external leakage types. Based on the unloading condition caused by the medium at the end face, it can be divided into balanced and unbalanced types. Based on the logarithm of the sealed end surface, they can be classified as single-end and double-end. Based on the number of springs, they can be divided into single-spring type and multi-spring type. Classified by elastic elements: spring compression type and bellows type. Classified by the structure of non-contact mechanical seals: hydrostatic type, hydrodynamic type, and dry gas seal type. Classified by seal chamber temperature: high, medium, standard, and low-temperature sealing. Classification by seal chamber pressure: ultra-high, high, medium, and low-pressure mechanical seals. II. Stirring in the tank generally refers to shaft sealing, which can be achieved using packing seals, mechanical seals, or dynamic seals. 1. Packing seals have a simple structure, are inexpensive, and are easy to maintain. But it has a large leakage rate and high power consumption losses. Therefore, packing seals are used for transporting ordinary media such as water ； It is generally not suitable for petroleum and chemical media, especially not for valuable, explosive, or toxic substances. 2. Mechanical seals (also known as face seals) offer excellent sealing performance, very low leakage rates, and a long service life; however, they are expensive, and their processing, installation, and maintenance require higher standards compared to ordinary seals. Mechanical seals are suitable for transporting petroleum and chemical fluids, and can be used with fluids of various viscosities, high corrosivity, or containing particles. Standard API610 (8th edition) of the American Petroleum Institute specifies that, unless specified by the user, a cartridge mechanical seal shall be installed. 3. It features reliable dynamic sealing performance, low cost, and easy maintenance; it is suitable for transporting media containing a high amount of solid particles, such as slurry pumps and pulp pumps used in the phosphate industry. The disadvantage is that the power loss is greater compared to mechanical seals, and the lifespan of its shutdown sealing device is shorter.

It is used for transporting petroleum and chemical fluids, and for sealing various valves and flanges; it comes in hard-seal and soft-seal types. Various gaskets are also common.

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