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Leakage Phenomenon Of Mechanical Seal Of Water Pump And Its Countermeasures
Feb 27, 2018

Leakage phenomenon of mechanical seal of leaking water pump and its countermeasures

Mechanical seals also known as end-face seals, which have a pair of perpendicular to the axis of rotation of the end face, the end of the fluid pressure and compensation mechanical external elasticity, depending on the auxiliary seal, and the other end of the fitting, and relatively sliding, thus preventing fluid leakage.

Common periodic leakage

Common periodic leakage

1, the pump rotor axial channeling momentum is large, auxiliary seal and shaft of excessive interference, dynamic ring can not be flexible on the axis of movement. When the pump is flipped, the dynamic and static ring wear out and the compensation displacement is not.

Countermeasures: In the assembly of mechanical seals, axial channeling momentum of the shaft should be less than 0.1 mm, the auxiliary seal and the shaft of the surplus amount of moderate, in the guarantee of radial seal at the same time, the dynamic ring assembly to ensure the flexible movement on the axis (the dynamic ring pressure to spring can be free to bounce

2, the sealing surface of the lack of lubricating oil caused by dry friction or nap seal end face

Countermeasures: Oil-cavity lubricant oil surface height should be higher than dynamic, static ring sealing surface

3, the rotor periodic vibration, because the stator and upper, lower cover is not in the middle or impeller and spindle imbalance, cavitation or bearing damage

Ii. leakage caused by pressure

1, high pressure and pressure wave caused by mechanical seal leakage

Because the spring ratio pressure and the total pressure design is too large, the pressure in the sealed cavity exceeds 3Mpa, it will make the seal face than the pressure, the liquid film is difficult to form, seal face wear seriously, increase calorific value, resulting in thermal deformation of the sealing surface.

Countermeasures: In the assembly of mechanical seals, the spring compression must be in accordance with the provisions, not allowed too large or too small. Mechanical seals under high pressure conditions should take measures to make the end face load reasonable, the use of hard alloy, ceramics, such as high compressive strength materials, and strengthen the cooling lubrication measures.

2, vacuum state operation caused by mechanical seal leakage

Pump in the process of starting and stopping, because of the pump inlet blockage, the pumping medium contains gas and other reasons, it is possible to make the sealing cavity negative pressure, which causes the sealing surface dry friction.

Countermeasure: Adopt double end surface mechanical seal, this can improve lubrication condition, improve sealing performance. Iii. leakage caused by media

The particles in the medium, impurities into the sealing surface, so that the seal failure, dynamic, static ring auxiliary seal due to the medium weak acid, weak base corrosion, loss of due function.

Countermeasures: To ensure that the lower cover, the cleanliness of the oil chamber, the installation of the unclean lubricant is prohibited; The oil surface line in the mechanical seal oil chamber should be higher than the cover; according to different media, mechanical seals of different structure, such as corrosive medium, rubber parts should choose high-temperature resistance, weak acid, weak base of fluorine rubber, The mechanical seal of tungsten carbide friction pair is selected in the position where the solid particles are easy to enter.

Iv. leakage of mechanical seals due to other problems

Mechanical seals exist in the design, selection, installation and other unreasonableplaces

Countermeasures: Spring compression error should be in-2 mm-2 mm, too large to increase the end-face pressure, excessive friction heat, easy to cause hot deformation of sealing surface and accelerated end wear, too small, static ring end of the pressure is not enough, can not be sealed; the end face of the seal gland (or shell) of the movable ring seal ring should be chamfer and repaired. In order to avoid the assembly of touch, static ring seal ring.

Above summarized the mechanical seal more common leakage reason and the countermeasure. The mechanical seal itself is a high precision component. In use, should analyze various factors, so that mechanical seals applicable to a variety of pump technical requirements and the use of media requirements, so as to ensure long-term reliable operation.

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