What Is a Mechanical Seal?

Mechanical seals prevent leakage and contamination of process fluids and gases during transportation via rotating equipment, like pumps, mixers, steam turbines, or compressors.

fragment of the end sealer to prevent leaks in the oil and gas industry

Published June 02, 2021   |   3 minute read

Mechanical seals are the unsung heroes of industrial processing. They may be small, but they are absolutely critical to ensuring environmental safety and process integrity. Choosing the wrong seals, however, can lead to expensive equipment failures and downtime, so choosing the right model for your intended application is essential.

Here’s everything you need to know about mechanical seals.

What is a mechanical seal?

Simply put, a mechanical seal is a device used to contain pressurized fluid or gas to prevent leaks. You’ll most often find mechanical seals on rotating equipment such as pumps, compressors, mixers, steam turbines, and blowers.

Why is a mechanical seal necessary?

Without a proper seal in place, the high pressures used to transport liquid or gas within a pump or compressor will force that same liquid or gas out into the external – or lower pressure – environment, resulting in leaks, waste, and environmental concerns.

Mechanical seals are important for two main reasons:

  • As environmental regulations become more stringent, preventing leakage is critically important to thwarting potential waste and environmental harm, and avoiding costly fines and clean-up fees associated with leak events.
  • While processing and / or transferring substances, the right mechanical seal and seal piping plan can also prevent contamination of the process fluid, thereby preventing yield reductions.

Furthermore, while pump packing is a popular method of preventing leakage, it’s not nearly as efficient as using a mechanical seal, as this practice increases operating horsepower and damages the equipment shaft.

How does a mechanical seal work?

Mechanical seals have three core components: the stationary and rotating faces that comprise the primary seal, plus the static elements like elastomers and gaskets. The stationary part fits into the pump housing and are sealed with a static gasket or O-ring. Meanwhile, the rotating portion locks onto the pump, mixer, or compressor shaft and rotates with a very thin gap between it and the stationary face, which creates a tight orifice that reduces the higher sealing chamber pressure down to atmospheric pressure.

Mechanical seals work in one of two ways: either a rotating shaft moves through the stationary housing, or the housing rotates around the shaft. This configuration largely depends on application and sealing needs, though rotating shafts are much more common.

Depending on what kind of seal you use, either the stationary or the rotary components will be installed with spring loading to accommodate any shaft movements and manufacturing tolerated misalignments – i.e., misalignments that are within acceptable use parameters and do not require correction.

How do you choose the right mechanical seal for your system?

When designing your system, you should keep in mind that all mechanical seals require lubrication between the seal faces to reduce friction and prevent damage, or even breakage, as the two faces slide past each other.

There are so many different kinds of mechanical seals on the market right now, all with different installation and maintenance needs, that determining the optimal one may seem overwhelming.

Your best bet is to consult with an experienced company staffed with a knowledgeable team of highly trained experts, such as Sunair.

Sunair Co. has provided customers with high-quality commercial and industrial equipment, including mechanical seals, to organizations large and small, for all industries and applications, since 1974. We hand-pick our sales team for their expertise and ability to design custom systems for our clients.

For more information or to get started on choosing the right mechanical seal for your system, contact us today

When developing a system for processing and transferring liquids, gases, and slurries, the pumps and compressors you choose are central to ensuring reliability and maximum efficiency, no matter your industry or application. They’re not the only components that matter, however.

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