Using the right mechanical seals for your production?

Mechanical seals may be small, but their importance is anything but microscopic. They are the silent guardians that keep the medium inside the pump and contamination out of your end product. But if the seal is not the perfect match for your process, these small components can quickly become an expensive pleasure in the shape of leaks, product waste and unplanned stoppages that always happen at the worst possible time. 

Many plants today operate with solutions that only partially match the actual operating conditions. Perhaps you have changed media, or cleaning routines have changed since the equipment was purchased. This article provides a practical guide to what you need to be aware of and how you can assess whether you are using the right mechanical seals in your production. 

A mechanical seal – often called a stuffing box – ensures that liquids and gases remain within the desired limits in rotating equipment such as pumps, mixers and agitators. It forms a tight barrier between the rotating axle and the pump house and prevents the medium from leaking into the environment – or unwanted substances from entering the product. 

In hygienic applications, the mechanical seal protects both the end product and system modules from contamination and is therefore a critical component in food, dairy and pharmaceutical production. That is why it is important to choose a sealing solution that matches both technical requirements, media and process environment. 

When choosing the right mechanical seal, it is important to match the seal to both the process and the equipment – otherwise you risk leaks, unnecessary production stoppages and impaired hygiene. Start by defining a few key parameters: 

• What type of pump or equipment are you working with (e.g. APV, Alfa Laval, Fristam, Hilge or Jabsco)? 
• What product is being pumped, and what are the temperature and pressure conditions during operation? This also includes whether CIP or SIP cleaning is used.  

At this stage, many incorrectly selected seals can already be ruled out. Finally, you should look at the materials in the mechanical seal itself, as they are very important for both service life and operational reliability. 

Next, you should zoom in on the material composition of the mechanical seal itself, as this has a significant impact on both service life and operational reliability. The rotating and stationary parts are usually made of materials such as carbon, ceramic, stainless steel, silicon carbide (SiC) or tungsten carbide (TC). The choice between these should be made strategically based on the wear resistance of the medium and the mechanical load. 

You can therefore ask yourself: Do we work with clean, thin liquids, or does our medium require materials that can withstand heavy friction? 

You achieve the best operational reliability when you choose gasket material with the same care. Whether you choose NBR, EPDM, viton/FKM or PTFE, the material must not only withstand your product, but also the temperatures and chemicals that your cleaning cycles expose them to. The wrong match is often the direct cause of a seal failing prematurely. 

If you have to choose between soft vs. hard (e.g. carbon vs. Sic/Cer) or hard vs. hard (Sic vs. Sic, TC vs. TC), in practice it is a question of whether you prioritise low friction and gentle operation – or maximum wear resistance in demanding media. In addition, you should always choose the packing material so that it can withstand both the medium and the cleaning chemicals. Otherwise, the service life will be short, regardless of how correctly the friction pair is selected. 

In the video, we show you how they work and why materials such as carbon, ceramics and silicon carbide, as well as the role of liquids, are so important. 

We stock a wide range of mechanical seals that meet the OEM specifications for the most widely used pumps in the process industry. This means that in many cases we can deliver the right mechanical seal from day to day – and in other cases we can obtain it quickly through our close cooperation with manufacturers. 

If you need advice on whether you are using the right mechanical seals for your production, we are happy to help you: 

• Matching existing pumps and equipment with compatible seals. 
• Optimising material selection in relation to media, temperature, pressure and cleaning. 
• Reducing downtime and spare parts consumption through better sealing solutions. 

Feel free to contact us by phone on +45 7020 0422 or by email at inquiry@alfotech.eu for a no-obligation chat. You can also go directly to our overview of mechanical seals, where you can find the solution that suits your equipment.