fuyangby@126.com
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fuyangby@126.com
86 15188770013
Principle and mechanism of secondary impeller sealing
Basic principles
The secondary impeller seal relies on fluid dynamic action for sealing and belongs to non-contact sealing. Air or clean water generates pressure under the rotation of the secondary impeller, and forms an air or water slurry equilibrium with the slurry on the outer edge of the secondary impeller, thereby resisting the leakage of liquid at the outlet of the main impeller.
Specific mode of action
Resistance to leakage: The pressure head generated by the secondary impeller can directly resist the leakage trend of the liquid at the outlet of the main impeller, preventing the slurry in the pump body from leaking between the shaft and the pump body.
Prevent air from entering: Use the impeller cover plate to install a back blade water seal ring and packing. The back blade and water seal ring can reduce the pressure at the packing area, preventing air from entering the pump and also preventing impurities from entering the sealing area.
Structural type and characteristics
There are two structural types of secondary impeller seals: metal pressure relief cover secondary impeller seals and rubber pressure relief cover secondary impeller seals. Generally, the former is relatively more common, but secondary impeller seals have the disadvantage of high power consumption and are mainly used to seal low-pressure liquids containing impurities.
Principle and mechanism of mechanical seal
Structural composition
The mechanical seal structure consists of a moving ring (which rotates with the shaft and can move axially), a stationary ring, a clamping element (spring), and a sealing element (sealing ring). Some people also believe that mechanical seals consist of a static ring, a dynamic ring, a compensating buffer mechanism, an auxiliary sealing ring, and a transmission mechanism.
Working principle
Forming a sealing surface: The dynamic ring relies on the pressure of the clamping element (spring) and the pressure of the liquid in the sealing chamber to make its end face adhere to the end face of the static ring. Under the action of pressure and relative rotational motion, the dynamic and static rings establish fluid dynamic lubrication between their end faces.
Mechanical seal selection guide
Blocking leakage pathways: The tightly attached dynamic and static ring end faces work together with the sealing ring to block all possible pathways for fluid leakage from the pump chamber, thereby establishing a sealing structure between the rotating component (shaft sleeve or shaft) and the stationary component (pump casing), achieving the purpose of sealing.
Special design and function
Double end mechanical seal and cooling water system: For example, ZJ slurry pump adopts a double end mechanical seal structure and is equipped with a cooling water system. This system can reduce the temperature of the friction area, extend the service life of the mechanical seal, and adapt to the working conditions where the slurry pump conveying medium contains a large amount of particulate matter and hard materials such as sand and gravel.
Material selection: Static rings are usually made of soft materials with good wetting properties such as high-purity graphite and filled PTFE, while dynamic rings are made of materials such as tungsten steel and ceramics to ensure sealing and wear resistance.
INSTALLATION REQUIREMENTS
The principle of mechanical seal requires that there be no residue inside. Before assembling the mechanical seal, the moving ring, stationary ring, shaft sleeve and other components should be cleaned, and the surface of the moving and stationary rings should be checked for scratches, cracks and other defects. If necessary, fixtures can be made for pressure testing before assembly to check whether there are defects affecting the sealing of the moving and stationary ring seats.
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(Editor in charge: Slurry Pump https://www.fuyangpumps.com/)
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