German dafa seals dafa models dafa prices

dafa seals are the customary term for general seals; simply put, they are seals for lubricating oil. They are mechanical components used to seal grease (oil is the most common liquid in transmission systems, and the term also refers to general liquids). They isolate lubricated parts in the transmission from output parts to prevent lubricating oil leakage. Seals used for static sealing and dynamic sealing (generally reciprocating motion) are called oil seals. The representative form of oil seals is the TC oil seal, which is a double-lip oil seal with a self-tightening spring fully covered by rubber. The term oil seal generally refers to this type of tc skeleton oil seal.

dafa seal principle

A mechanical seal is a shaft sealing device that prevents leakage by keeping one or more pairs of end faces, which slide relative to each other perpendicular to the shaft, in contact under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism, supplemented by auxiliary seals. A common mechanical seal structure consists of a stationary ring (static ring), a rotating ring (dynamic ring), an elastic element spring seat, set screws, a rotating ring auxiliary O-ring, and a stationary ring auxiliary O-ring. An anti-rotation pin is fixed to the gland to prevent the stationary ring from rotating. The rotating ring and stationary ring can also be referred to as compensation rings or non-compensation rings, depending on whether they have axial compensation capability.

dafa seal system composition

1) Seal chamber: In the past, seal chambers housing mechanical seals were stuffing boxes designed for soft packing seals. They are unsuitable for housing mechanical seals, not only because the dimensions are too small and the clearances too narrow, but also because the simple cylindrical shape is inappropriate. Standards for enlarged mechanical seal chambers have been established abroad. In addition, Durametallic Corporation in the United States and the Fluid Engineering Study Group in the United Kingdom are studying reasonable mechanical seal chamber designs. Their shapes should not only facilitate fluid flow and heat dissipation but also help remove solid particles, creating a favorable environment for the seal. 2) Volatile organic compound (VOC) emission control system: In the past, attention was focused only on eliminating visible fluid leaks, while invisible VOC emissions were neglected, resulting in environmental pollution and hazards to equipment and personnel. Organizations abroad, such as the Sealing Technology Committee of the Society of Tribologists and Lubrication Engineers (STLE) in the United States, have developed guidelines for controlling volatile emissions in rotating machinery, compressors, and screw systems with mechanical seals, including SP-30 (1994), SP-32 (1990), and SP-33 (1991). SP-30 is implemented in three phases. It clearly defines barrier fluids and buffer fluids, clarifying erroneous and confused concepts. A barrier fluid is introduced between dual seals to completely block process fluid from leaking into the surrounding environment. The pressure of the barrier fluid is always higher than the pressure of the sealed process fluid. A buffer fluid is used between dual seals as a lubricant or buffer, and its pressure is always lower than the pressure of the sealed process fluid. 3) Auxiliary system integration: Mechanical seal auxiliary systems require integration of cooling, heating, and flushing systems. Pump circulation needs optimization, and condition monitoring systems are being studied and resolved. Auxiliary system integration is specified in the API-682 standard. 4) Gas barrier seal system: In the past, liquid-blocking-liquid or liquid-blocking-gas configurations were commonly used in barrier seal systems. To simplify bulky barrier liquid systems, barrier gas is now used to block liquids or gases. Gas barrier seal systems may employ spiral groove gas seals with barrier gas, floating bushings with barrier gas, etc., to block gases and liquids.

dafa seal installation technical requirements

Mechanical seals are high-precision mechanical components, and their correct installation and operation significantly impact service life. We generally follow the standards specified by the Ministry of Petrochemical Industry. The technical requirements for the pump and the mating parts of the mechanical seal are as follows: 1) Shaft runout: maximum not greater than 0.05 mm; 2) Rotor vibration: near the shaft sleeve at the dynamic ring seal location, not greater than 0.06 mm; 3) Axial shaft movement must not exceed ±0.5 mm; if a shaft sleeve is present, it must not be loose; 4) Coupling alignment error: for gear couplings, not greater than 0.08–0.10 mm (P2008C); for elastic couplings, not greater than 0.05–0.06 mm; (customary practice: face runout<0.05, radial runout<0.10) 5) Concentricity tolerance of the gland (static ring seat) and the seal mating spigot relative to the shaft centerline: 0.05 mm; perpendicularity tolerance of the surface contacting the gasket relative to the centerline: 0.03–0.05 mm. If these requirements are not met, the seal chamber must be machined; 6) The ends of the shaft sleeve where the dynamic ring seal is installed, and the ends of the gland (or housing) where the static ring seal is installed, should be chamfered and smoothed. 7) Exercise care during installation and removal of mechanical seals. Do not use hammers or flat chisels to avoid damaging seal components. If scaling prevents removal, clean thoroughly before disassembly. 8) If mechanical seals are used on both ends of the pump, coordinate during assembly and disassembly to avoid neglecting one side while attending to the other. 9) For mechanical seals that have been in operation, if gland loosening has caused seal movement, the stationary and rotating ring components must be replaced. Do not simply retighten and continue use, as loosening alters the original running track of the friction pair, easily compromising the sealing integrity of the contact surfaces.

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