Mechanical seals are critical components in centrifugal pump systems. These devices preserve the integrity of the pump systems by keeping the fluid contained within the pump while the internal mechanical components move inside the stationary housing. When mechanical seals fail, the resulting leaks can cause extensive damage to the pump and often leaves large messes that can be significant safety hazards. Besides being a crucial component to a pump running efficiently, mechanical seals are also the most common culprit of pump downtime.
Understanding the cause of mechanical seal failure can help end users with preventative maintenance and ultimately extend the service life of their pumps. Our service pros at IndustriTech often diagnose preventable mechanical seal failures, which result in unplanned downtime and costly repairs. Here are the four most common reasons for failure:
1. Using the wrong type of mechanical seal
It is extremely important that the mechanical seal you are using is correct for the application. Mechanical seal types vary in design, arrangement, and how they disperse the hydraulic forces acting on their faces. Numerous factors like pump specifications, temperature, fluid viscosity, and chemical aspects of the fluid are all determinants in which mechanical seal is right for the job. Even experienced engineers can sometimes miss certain aspects which result in mechanical seals that do not meet the needs of the application. The best way to ensure you are using the correct mechanical seals is to consult with pump specialists that can take a look at the entire application and recommend mechanical seals based on all contributing factors as well as proven experience.
2. Running the pump dry
When a pump operates without adequate liquid it is referred to as 'running dry'. During normal operation, the fluid being handled will fill the flow space inside the pump, helping to cool and lubricate the mechanical seal components in contact with each other. Without this fluid, the lack of cooling and lubrication can cause internal components to overheat and start to fail. Seals can overheat and disintegrate in as little as 30 seconds when running the pump dry.
There are a variety of factors that can lead to excessive vibration in a pump, including improper installation, misalignment, and cavitation (read more about the cause and effect of vibration on rotating machinery here). While mechanical seals aren't a contributing factor to vibration, they will suffer along with other internal components when pump vibration exceeds acceptable levels.
4. Human error
Any operation of a pump outside of its intended specifications and usage can cause damage to its components and run the risk of failure, including the mechanical seals. Improper installation, improper start-up, and lack of maintenance can wear down seals and eventually cause them to fail. Mishandling of seals prior to installation and introduction of dirt, oil, or any other abrasive material can also cause damage that gets worse as the pump runs.
Mechanical seals are a common pain-point in pumping applications and there are a wide variety of reasons for failure. Choosing the correct mechanical seal, proper installation, and proper maintenance will help to ensure mechanical seals deliver a long service life. With decades of experience in the industrial pump market, IndustriTech is well equipped to help with mechanical seal selection, installation, commissioning, and service. If your pump is experiencing issues, our in-house service pros can provide the expert and efficient service needed to get your equipment back on-line quickly, and to keep your fluid processing operation running as efficiently as possible and for as long as possible.