German dfv seals dfv model dfv price

dfv seals are a type of friction seal or stuffing box used to prevent liquid leakage between the shaft and bearing of compressors or other fluid handling equipment. They are also sealing devices installed to prevent leakage at the pump shaft and housing. Common types of shaft seals include packing seals, mechanical seals, and power seals. The shaft seal of a reciprocating pump is usually a packing seal. When transporting media where leakage is not permitted, a diaphragm reciprocating pump can be used. The shaft seals of rotary pumps (including vane pumps, rotor pumps, etc.) mainly consist of packing seals, mechanical seals, and power seals.

Introduction to dfv seals

A mechanical seal is a shaft sealing device for rotating machinery, such as centrifugal pumps, centrifuges, reaction vessels, and compressors. Since the drive shaft passes through the interior and exterior of the equipment, there is a circumferential gap between the shaft and the equipment. Media inside the equipment leaks outward through this gap; if the pressure inside the equipment is lower than atmospheric pressure, air leaks into the equipment. Therefore, a shaft sealing device is required to prevent leakage. There are many types of shaft seals. Due to advantages such as low leakage and long service life, mechanical seals are the primary shaft sealing method for these equipment worldwide. Mechanical seals are also called face seals. In relevant national standards, they are defined as: "A device that prevents fluid leakage by maintaining contact and relative sliding between at least one pair of faces perpendicular to the axis of rotation, under the action of fluid pressure and the elastic force (or magnetic force) of a compensation mechanism, in conjunction with auxiliary seals."

dfv seal structure and composition

1) Main components: rotating ring, stationary ring, cooling device, and compression spring (depending on the specific equipment). 2) Auxiliary sealing elements: sealing rings (including O-shape, X-shape, U-type, wedge shape, rectangular flexible graphite, PTFE-covered rubber O rings, etc.). 3) Elastic compensation mechanism: springs, thrust rings, spring seats, keys, or various screws. 4) Classification: divided into single-face and double-face; balanced and unbalanced; arbitrary rotation direction and fixed rotation direction.

dfv seal installation technical requirements

Mechanical seals are high-precision mechanical components, and their correct installation and operation significantly impact their service life. We generally follow the standards specified by the Ministry of Petrochemical Industry. The technical requirements for the pump installing the mechanical seal and the mating parts of the mechanical seal are as follows: 1) Shaft bending: maximum not greater than 0.05 mm; 2) Rotor runout: near the shaft sleeve at the rotating ring sealing ring, not greater than 0.06 mm; 3) Axial shaft movement must not exceed ±0.5 mm; if a shaft sleeve is present, the shaft sleeve 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; (common practice: end runout<0.05, radial runout<0.10) 5) Concentricity tolerance of the gland (stationary ring seat) and the sealing 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 requirements are not met, the seal chamber must be machined; 6) The end of the shaft sleeve where the rotating ring sealing ring is installed, and the end of the gland (or housing) where the stationary ring sealing ring is installed, should be chamfered and smoothed. 7) Be careful when installing or removing mechanical seals. Do not use hammers or flat chisels to avoid damaging sealing elements. If scale prevents removal, clean thoroughly before disassembly. 8) If mechanical seals are used on both ends of the pump, take care 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 causes seal movement, the rotating and stationary ring parts must be replaced. Do not simply retighten and continue using them, as loosening changes the original operating trajectory of the friction pair, easily compromising the sealing integrity of the contact surfaces.

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