mechanical face seals -
Unless the sealing surface is flat and remains flat during operation, the seal will not be tight.If the mechanical sealing surface is uneven, then the mechanical sealing will leak regardless of other parameters.In addition to this, the surface parallel to the plane is not only crucial to prevent leakage, but also to prevent grinding particles from entering between the surfaces of the mechanical seal.
Therefore, a good mechanical seal can not only meet its main function of preventing leakage, but also have a long service life.In order to obtain a flat mechanical sealing surface, a stable and symmetrical design is required.The spring pre-loaded surfaces ensure that they maintain constant contact even if the mechanical seals are not under pressure.
However, during the operation, the main closing force is the pressure applied from the sealed liquid to press the surface together.Static seals usually made of some kind of rubber form a fixed mechanical seal around the sealing ring.They are necessary to prevent leakage at the seams between the sealing ring and its fixed structure.
Static mechanical seal located around the spring-The loaded face is often called \"halfdynamic\\\".In other words, it must be able to change its position slightly in order to adapt to small shaft deflection and surface wear during the operation of the unit.Because there is friction between the mechanical sealing surface, there will also be torque transmission.
This may cause the face that should have been stationary to rotate in its shell, and the rotating face is separated from the axis.The best way to prevent this from happening is to fix the ring as firmly as possible on its fixed structure.This can be achieved by mechanical devices, such as pins, sleeve screws or washers, or by simply applying pressure around the ring, usually by compressing static rubber mechanical seals.
The lubrication state between surfaces is called \"mixed lubrication \".This means that when the surface moves with each other, the mixture of the liquid film and the direct contact between them.There are no macroscopic fluid dynamics features on the surface of the mechanical seal, such as grooves or steps, which inevitably produce a liquid film.
Even so, some liquid film is produced between smooth and flat surfaces.With the increase of surface load, the area of liquid film decreases and the area of direct contact increases.If the pressure on the two sides is too high, the area of direct contact will be too large and the mechanical seal will catch.
The location of the critical load point for each mechanical seal depends on the surface material, the balance ratio and the ability of the specific seal design to dissipate heat.If the seal is to be kept tight, the spring load must be high enough to overcomeDynamic static seal.At the same time, the spring load cannot be too high to cause unacceptable wear and heat.
Therefore, there is little room for change in the spring force.Therefore, the balance ratio is the main factor that determines how much pressure the mechanical seal is subjected.This ratio is the ratio between the external area of the mechanical seal ring (where the external liquid pressure is applied) and the area of the actual sealing surface.
The size of this ratio is determined by the design of the seal.The basic lay-The sealing system of all Flygt products is the same;External mechanical seal, oil-Full Chamber and internal seal.The outer seal is one of the two SEALs that is more refined.
Its surface is made of wear-resistant materials such as hard alloy, hard alloy or alumina.Since the internal seal is protected by the oil tank, the wear is small.Therefore, one of these two faces is made of carbon, which exhibits very good sliding properties despite relatively low wear resistance.
However, hard-Where additional protection is required to prevent grinding, the surface inner seal can be used.The outer seal and the inner seal operate independently from each other.The oil in the mechanical seal compartment has three major functions;Lubrication, cooling and emulsion of leakage.
Lubrication and cooling functions are quite self-containedIt is clear that if there is no oil, the sealing surface will quickly overheat and get stuck.The emulsion function includes dilution and suspension of liquids and particles that may leak through the seal.These contaminants may form deposits, thus blocking or damaging the seal.
The mechanical seal does not rely on rubber friction when transmitting torque between the shaft and the sealing ring.Instead, there is always a mechanical device to ensure a positive drive.It\'s a bit expensive but much more reliable.
Since static rubber mechanical seals are not required as torque locks, it is not necessary to clamp them so tightly.This facilitates assembly and disassembly.The seal does not have to be installed in a narrow sealing cavity originally used for sealing.
The seal design is not limited by this and can take advantage of the radial space of its components.This makes the seals, springs and O-The rings should be fully grasped and the seals should be short as these parts do not need to be stacked together.Short seals mean the transmission shaft can be short.
The short drive shaft minimizes impeller deflection and bearing load, thus improving the performance and service life of the product