Mechanical Seals: The Basics of Fluid Pump Sealing

Blog | July 14th, 2020

A few years ago, many companies find it difficult to switch to mechanical seals because of the complicated process of installation and disassembly of equipment. These companies would love to just stick with pump packing. However, the creation and invention of more variations of mechanical seals have allowed companies to easily install them with their equipment and devices.

Principles of Mechanical Seals

Mechanical seals are hardware devices that help combine two systems or mechanisms. And once they are installed, these seals can easily assist the systems or mechanisms in preventing leakage, containing pressure, or eliminating contamination. The adhesion of sealants and the compression of gaskets both determine the effectiveness of the seals on their respective applications.

Some systems or mechanisms that mechanical seals combine include pumps and mixers. One component of these seals is mostly stationary, while the other one rotates against it. The way mechanical seals are designed helps them achieve a great seal against all types of leakage.

Adoption of Mechanical Seals

Mechanical seals have a rotating shaft that passes through their stationary housing. There are instances, however, wherein the stationary housing rotates around the said shaft. What makes these seals suitable for various industries is that the friction of the rotating shaft does not wear out easily. They also do not need to be flushed with large volumes of water just for them to keep cool.

The overall design of mechanical seals also allows them to prevent any damages and high energy consumption since they do not have to press against and be in contact with the shaft all the time.

The Design and Sealing Points

Mechanical seals have three sealing points. The stationary part of mechanical seals is typically sealed with an O-ring or gasket to the pump housing. The rotary portion of the mechanical seals, on the other hand, is sealed by an O-ring onto the shaft. This portion is still part of the static sealing point since it still rotates with the shaft. The interface between the static and rotary parts of the seal is the mechanical seal itself. To accommodate any small shaft deflections, shaft movement, and out-of-perpendicular alignment, one part of the seal is designed to be always mounted and spring-loaded.

Two of the sealing points in mechanical seals are static, while the primary seal takes the form of a spring-loaded bearing, wherein it has two extremely flat faces. One of these faces is fixed, while the other one rotates. These seal faces run against each other through the combination of hydraulic force and spring force. These forces help prevent any leaking situations between the rotating and static components.

Importance of the Fluid Film

Just like any other seals, mechanical seals must also contain some sort of lubrication to avoid getting damages due to continuous friction and generation of heat. The lubrication for mechanical seals is known as the fluid film.

The faces of mechanical seals are lubricated all the time through a thin film of fluid that comes from either the process fluid being pumped or from an external source of lubrication. To prevent contaminants and even water from entering the seal, the gap between the faces is designed and maintained as little as 1 micron. This gap is then maintained by springs and hydraulic forces that push the seal faces together. The pressure of the liquid between the faces then acts to set them apart to avoid full contact and seal failure. All these elements of mechanical seals allow them to be usable and suitable for fluid pump sealing. If you have more questions about these seals, feel free to give us a call at Mobile Hydraulic Specialties.

Mobile Hydraulic Specialties Pty Ltd

Factory 89, 38-40 Popes Road
Keysborough, Victoria, 3173

Phone: (03) 9798-6511

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Contact Us

Mobile Hydraulic Specialties Pty Ltd

Phone: (03) 9798-6511
Address: Factory 89, 38-40 Popes Road, Keysborough, Victoria, 3173