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Shaft seals manufacturers have introduced a lot of seals for various machines. Modern machines cannot work without good and reliable rubber seals. In this article we will go through the various types of shaft seals and their functions.
Generally, the shaft seal determines the tightness of the housing of this or that unit and the shaft joint. Questions about the type and size of the sealing elements are good to ask at the stage of production of the mechanism. When choosing parts, it is very important to pay attention to such operating conditions of the environment as:
Moreover, these parameters directly affect what materials must be good for the manufacture of elements.
In modern machines and equipment that perform mechanical works with the rotation of mechanisms. Moreover, it is necessary to ensure the tightness of the working cavity and the rotating shaft passing through it. For this, shaft seals manufacturers use sealing devices of various designs.
Hence, these seals can also serve to retain lubrication. And it prevents the possibility of intrusion of foreign debris that could damage equipment and lead to premature failure.
In addition, the conditions of use of seals can vary significantly from each other. Therefore, the designs of these sealing assemblies are improving. It is in order to meet certain operating parameters.
While some seal applications may allow slight leakage, others may not. As the parameters of the working environment and requirements need:
Hence, it has become more and more stringent for shaft seals manufacturers. Simultaneously, the design of seals became more complex and their inevitable rise in cost. Furthermore, we can divide Shaft seals into two groups:
Generally, contact seals interact with the surface of the rotating shaft. It is due to the creation of a certain contact pressure between their mating surfaces. Furthermore, the tightness is very important, but friction and wear of the seal and / or shaft surface appears.
There are three types of contact seals.
Lip (radial) seal
Lip seal (lip or radial seal) is mainly important to retain lubricant and exclude external contamination of the cavity and elements of machinery and equipment. Such a sealing device is capable of operating in a temperature range of -40 to 200 degrees Celsius with low pressure drops. Moreover, the indisputable advantage of cuffs is their low price, small dimensions and ease of installation.
Due to the design features, radial lip seals have limitations in their applicability in terms of pressure and sliding speed. It is due to friction they gradually wear out themselves and caricature the shaft surface in the contact area. Similarly, it forms local circular wear on it. Lip shaft seals are good for pumps with low shaft speeds at an overpressure of up to 0.5 atmospheres. For reliable shaft seals, contact only professional shaft seals manufacturers.
Generally, the stuffing box packing does not provide a high degree of tightness. The gland packing comes in such a way that minimal fluid leakage provides the necessary lubrication.
This type of seal was used in outdated pumps and requires periodic maintenance. In recent decades, the stuffing box has inevitably lost ground to the mechanical seal.
End (mechanical) seal
The mechanical seal is a precision assembly. Moreover, it prevents leakage and is common for applications where lip and gland packing are not permitted. These seals generally have a long service life with little or no shaft surface wear. Subsequently, they do not require periodic maintenance.
NON-CONTACT (DYNAMIC) SEALS
The use of dynamic seals of this group always comes by a certain amount of leakage. Moreover, it depends on the size of the gap and the shape of the sealing surfaces and the rotating shaft. This clearance virtually eliminates friction between the seal and the shaft.
A simple throat seal is a sleeve secured in housing through. It is very easy for shaft seals manufacturers to build it via new technology. Depending on the shape of the sealing surface, there are end and radial (axial) slots. Hence, the amount of leakage depends on the physical parameters of the working medium. Similarly, it has a cubic dependence on the height of the radial clearance.
The labyrinth seal is a slotted seal. It contains special grooves that drastically change the flow area of the channel. This type of seal is effective at high Reynolds numbers. Therefore; it does not require lubrication or periodic maintenance.
In the event of wear or damage to the sealing device, the leakage rate increases. Labyrinth seals are widely common in:
A magnetic fluid seal uses a colloidal suspension of magnetic particles (eg iron oxide) between the rotating shaft and the housing. It comes in place by the magnetic field of permanent magnets, to create a sealing effect like a hydraulic seal.
The design of such a unit has little wear (friction) and is insensitive to axial movement of the shaft. Shaft seals manufacturers use it mainly for gases and protection against the ingress of solid particles of dust and moisture.
The main reasons shaft seals are becoming more popular is because they allow machines to run faster, hotter and more efficiently for longer. Low friction increases efficiency, and low wear increases seal life, far beyond what can be achieved with conventional rubber seals. Shaft seals also allow manufacturers to offer extended service periods and extended warranties.
The mechanical shaft seal ensures the tightness of the pump housing. The effectiveness of a mechanical seal is determined by two main factors –
In simple words, the pump should not leak. Before proceeding to consider a rather complex device and types of mechanical seals.
Summarizing all of the above, we can conclude that the gland packing will be the cheapest and easiest to operate method of shaft sealing. We recommend using stuffing box packing (or its more modern counterpart – lip seal).
Perhaps this is the only question to which we will not give an unambiguous answer. You need to use only the original shaft seals manufacturers. More precisely, it is not entirely clear what is meant by “original”. The fact is that the vast majority of pump manufacturers does not produce mechanical seals on their own, but order them from companies such as dshseals, etc.