Introduction:
Mechanical seals (also known as face seals) are the core sealing components of rotating shaft equipment (such as pumps, reactors, and agitators). They form a sealing surface by tightly fitting the end faces of dynamic and static rings, preventing media leakage and isolating external contamination. They are widely used in harsh working conditions in many industries such as petrochemicals, pharmaceuticals, food, and new energy.
Core Structure and Working Principle
The core components include a rotating ring, a stationary ring, a spring, a sealing ring, and a bushing.
During operation, the preload generated by the spring and the pressure of the medium work together to ensure a tight seal between the rotating ring (which rotates with the shaft) and the sealing face of the stationary ring (fixed to the housing), forming an extremely thin liquid film (or gas film). This achieves both sealing and reduces wear on the sealing faces.
The sealing ring is used to seal the gaps between the rotating ring and the shaft, and between the stationary ring and the housing, further blocking leakage paths.
Core features and advantages
Excellent sealing performance: Leakage is significantly lower than that of packing seals (typically ≤10 drops/hour, with virtually no visible leakage in high-end applications), suitable for high-pressure and high-vacuum environments.
Long service life: The end faces are made of wear-resistant and corrosion-resistant materials such as hard alloy, silicon carbide, and graphite, resulting in minimal wear, longer maintenance cycles, and reduced equipment downtime.
Wide compatibility: Withstands a wide range of temperature (-200℃~800℃), pressure (0~40MPa), and speed (0~10000r/min), compatible with various media including water, oil, acids, alkalis, and organic solvents.
Low energy consumption: Low end face frictional resistance, resulting in greater energy savings compared to packing seals, especially suitable for high-speed rotating equipment.
Main types and applicable scenarios
Single-face mechanical seal: Simple structure, low cost, suitable for scenarios where the medium is non-toxic, non-corrosive, and allows for minor leakage (e.g., ordinary water pumps, agitator shafts of chemical atmospheric pressure storage tanks).
Double-face mechanical seal: Contains two sealing faces, with an intervening fluid (e.g., lubricating oil, inert gas) that can be injected between them. Suitable for toxic, flammable, highly corrosive, or high-purity media (e.g., pharmaceutical reactors, pump shafts of hydrogenation units).
Integrated mechanical seal: All components are pre-assembled into one unit, facilitating installation and ensuring high alignment accuracy. Suitable for large-scale production lines or rapid maintenance scenarios (e.g., pumps in food and beverage production lines, agitator shafts of lithium battery equipment).
Aseptic mechanical seal: Made of sanitary materials such as 316L stainless steel and PTFE, with no dead corners on the sealing surface. Supports in-line sterilization (SIP), suitable for aseptic scenarios in pharmaceuticals, vaccines, dairy products, etc. (e.g., agitator shafts of aseptic fermenters, aseptic mixing tanks).
Typical Application Industries:
Petrochemical Industry: Seals for agitator shafts of chemical pumps and reactors, resistant to corrosive media such as acids, alkalis, and organic solvents.
Pharmaceutical/Vaccine Industry: Seals for agitator shafts of sterile reactors and mixing tanks, conforming to GMP standards and preventing media contamination.
Food/Dairy Industry: Seals for agitator shafts of beverage pumps and yogurt fermentation tanks, hygienic, non-toxic, and leaving no media residue.
New Energy Industry: Seals for pump shafts of lithium battery material reactors and hydrogen storage equipment, resistant to special media such as electrolytes and hydrogen.
General Machinery Industry: Shaft seals for equipment such as water pumps, compressors, and centrifuges, ensuring stable equipment operation.
