Mechanical seals are key elements for optimal sealing in industrial machinery that requires fluid circulation. Equipment like pumps or compressors are prone to liquid leaks that reduce performance and eventually lead to breakdowns over time. Therefore, it’s essential to choose the right mechanical seal to boost installation reliability and reduce unexpected maintenance downtime.
At Lidering, we’ve been studying the behaviour of mechanical seals for years to meet the most demanding needs of our clients. In this article, we’ll explain in detail what a mechanical seal is, how it works, what alternatives exist, and which one best suits each type of use.
What is a mechanical seal and how does it work?
A mechanical seal is a dynamic element that seals the leakage point between two parts that move relative to each other. In the case of pumps, for example, the shaft spins pulling an impeller while the casing remains fixed, so the mechanical seal would be placed between the two parts to prevent fluid from leaking out.
The system consists of two seal faces: one stationary, attached to the equipment structure, and the other rotating, mounted on the shaft. Both stay in constant contact by a spring that compensates for small movements and vibrations in the system. Each face seals statically with its respective component (in this case, the structure and the shaft) using an elastomer, which completes the seal.
Comparison between mechanical seals and other sealing elements
Mechanical seals are not the only solution for sealing rotating equipment, but they have been the most widely used for decades. The most well-known alternative is gland packing, which, although it generates pressure between the material and the rotating shaft, needs a small, controlled leak to operate with some lubrication and avoid potential damage.
For decades, mechanical seals have been replacing gland packing in most industrial uses as they provide a much more effective seal and significantly reduce energy consumption due to friction.
Below is a table comparing the three most well-known sealing systems along with their key features:
| Sealing system | Sealing level | Needs controlled leak | Maintenance |
| Mechanical seal | Practically total | No | Low, if well aligned |
| Gland packing | Partial | Yes | Frequent, due to wear |
| Lip seal | High, but only with low pressures and temperatures | No, but the lip does need lubrication | It should be completely replaced after each disassembly. |
Types of mechanical according to design and materials
There is no “universal” mechanical seal that fits all types of uses. The design and suitable materials will vary depending on the equipment operating pressure, temperature and fluid. Therefore, it’s essential to choose the right combination to avoid early breakdowns and extend the lifespan of the installation. Next, we’ll briefly explain the most common alternatives:
- Multi-spring seals: they have several small springs distributed around the shaft. They’re perfect for large shaft sizes and clean fluids.
- Rubber bellows seals: The bellows itself acts as a sealing element and a transmission of rotation. A very simple, versatile and cost-effective solution.
- Cone spring seals: featuring a single larger spring, with a simple design and dependent rotation direction. This spring is responsible for transmitting shaft rotation. Common in standard general-use applications.
Seal face materials
Seal faces are the part of the seal subject to the most wear. They can be made from different materials depending on the type of use. The table below summarises these materials along with their main advantage and recommended uses:
| Seal face material | Strength | Recommended use |
| Silicon carbide | Hardness and chemical resistance | Abrasive or aggressive fluids |
| Tungsten | Good resistance to impacts | Uses with impacts or vibrations |
| Alumina | Lower cost | Low-demand uses |
| Graphite | Good self-lubrication | Systems with limited lubrication |
Elastomer materials
Elastomer is the material responsible for static sealing and also varies depending on the fluid and working temperature. The most commonly used are nitrile, EPDM, fluoroelastomer and perfluoroelastomer, each with its own characteristics regarding chemical compatibility and temperature range. Choosing the right elastomer is therefore just as important as picking the right seal face as using a variety that’s incompatible with the fluid can speed up degradation and cause leaks in no time.
Benefits of mechanical seals for industrial machinery
Installing the right mechanical seal brings benefits that can be seen directly in daily operations. Some examples would be reducing friction between the seal faces, which translates into less power loss, and lower equipment energy consumption compared to gland packing. They also provide nearly total sealing, which minimises fluid leaks and reduces both environmental risk and material waste.
All this leads to real long-term savings from fewer breakdowns, less waste generated and unplanned production line stoppages. A seal that is properly aligned, free from vibrations and operating at the right temperature maximises durability. This reduces repair costs compared to other sealing systems.
In summary, the key benefits of mechanical seals would be:
- Less friction and power loss thanks to optimal lubrication and spacing between faces.
- Long-term profitability due to reduced leaks, breakdowns and waste.
- Easier, cheaper and more spaced maintenance if the seal is properly installed.
- Less wear on the equipment when the seal is properly aligned and installed.
- Practically total sealing, far superior to other sealing systems.
How to choose the right mechanical seal for your installation
Before choosing a mechanical seal, consider the temperature range of use, the working pressure, type of fluid in the machine and the work environment. If any of these four conditions are not met, the part is highly likely to fail prematurely, regardless of its manufacturing quality Therefore, it’s necessary to determine which one fits best for each specific use.
At Lidering, we analyse each case individually to recommend the best combination of design, seal face material and elastomer for your specific installation.
Trust Lidering for your next mechanical seal
At Lidering, we specialise in mechanical seals and industry-related products related, and we can help you find the best solution for your installation. If you have any questions, don’t hesitate to get in touch with us and our team of specialists will be more than happy to help.
