What are Mechanical Seals?


On rotating equipment, such as pumps and mixers, mechanical seals are used as leakage control devices to stop gases and liquids from leaking into the environment. Two basic parts make up a mechanical seal. To form a seal, one component rotates in opposition to a stationary counterpart. Mechanical seals come in a wide variety of styles, from straightforward single-spring designs to significantly more intricate cartridge seal types. Pressure, temperature, speed of rotation, and the product being sealed are the main factors influencing the construction’s design, layout, and materials (the product media).


How does a mechanical seal function?


Four parts make up a mechanical seal: an elastomeric secondary seal, a flat rotating seal face, a flat stationary seal face, and a spring mechanism. A spring mechanism forces the two seal faces to come together. Carbon, ceramic, or metal are frequently used as seal faces. An elastomer secondary seal will be used in mechanical seal applications as well as a primary seal to seal the stationary face and the shaft. The basic parts of a mechanical seal are those, but to decide which one is best for your purposes, you’ll need a greater understanding of each component. Pumps and mixers with moving parts use mechanical seals to keep their fluids from leaking. In applications where a rotating shaft passes through a stationary housing—or, less frequently, in applications where the shaft is stationary and the housing spins around it—it is designed to contain liquid or gas. Any moving component will produce vibration, thus a mechanical seal must be precisely installed and made to resist typical vibration levels as well as the natural movement of the equipment. The longevity and productivity of machinery can be increased by installing a mechanical seal with the ideal design, size, and material. Please get in touch with us if you have any queries concerning the mechanical seals we offer.


Where are mechanical seals used?


Here are some instances of how a mechanical seal is used in a pump.

Mechanical seal in the pump’s design-


  1. Pump’s internal design

A pump is a device that moves fluids, such as when it lifts a liquid to its interior. To move water, for instance, its impeller revolves.


  1. Where is the mechanical seal installed in the pump?

On the shaft that rotates the impeller is a mechanical seal placed. This stops the liquid from seeping through the space between the shaft and the pump body.


  1. Location of mechanical seal installation on the shaft


A rotary ring on the shaft and a fixed ring on the pump housing make up the majority of mechanical seals.


  1. Mechanical Seal design (stationary and rotary rings)


The shaft and the rotary ring both rotate. In order to maintain a clearance between them in the order of micrometers, the stationary and rotary rings rub against one another. They are referred to as “facial materials” where they come into contact with one another.


The technologies that underlie mechanical sealing


Due to the aforementioned uses and functions, mechanical seal technology is a blend of physical property technology and mechanical engineering. The tribology (friction, wear, and lubrication) technology used to manage the surfaces where the stationary and rotary rings rub (slide) against each other is the fundamental component of mechanical seal technology, to be more precise.


Improved mechanical seals will not only stop a machine’s handling of liquid or gas from leaking to the outside but will also increase the efficiency of the machine’s operation, resulting in energy savings and the avoidance of environmental pollution. Additionally, spinning machines occasionally handle media that, in the event of a leak, could result in a risky accident. As a result, the manufacture of mechanical seals must be supported by strong engineering knowledge in order to provide high reliability.


Mechanical seals will become more and more crucial functional components as a result of these tasks and functions. We anticipate more technical advancements from them. Eagle Industry is always working on technical research and development to successfully meet these expectations.


How Are They Measured?


To precisely measure your mechanical seal, you must separate each component and compute its measurements separately:


  1. Check the interior diameter of the seal face after removing it from the spring. The size of the shaft or sleeve will be determined by this.
  2. The spring’s length after being separated from the seal face should then be determined.
  3. The stationary seat’s thickness, outside diameter, and interior diameter should all be measured.


Identify and cross-reference the suitable seal for your application after you have your measurements.


The Three Different Kinds of Mechanical Seals


In process equipment, mechanical seals come in three varieties:


  • Cartridge seal
  • Component
  • Air

Cartridge seal


A gland, sleeve, and hardware are housed in a cartridge-mounted, end-face mechanical seal, which is an entirely self-contained device. The manufacturer can preassemble and preset the unit thanks to a cartridge seal. Installation and maintenance are made simpler when these responsibilities are handled by the manufacturer. Depending on the needs of the application, cartridges may have one or two seals.


Component seal


A separate rotating part and a stationary seat that is mounted in a gland or housing make up component, end-face mechanical seals. Installation and maintenance are more difficult than with cartridge seals since they are not present. These installations require skilled personnel who can set them up and modify them correctly.


Air seal


Designed to seal rotating shafts, air seals are pneumatic, non-contacting devices. In dry powder or slurry applications, these seals are installed most frequently. Small volumes of air or inert gas are used to protect against product loss, emissions, and contamination. To provide positive pressure and a strong seal, this air is throttled.


Seal Components


Most mechanical seals consist of five components:


  • Rotating primary face- Seals against the stationary primary sealing element and is fixed to the shaft while rotating with it.
  • Stationary primary face- Fixed to the stationary housing of the pump, mixer, or another piece of machinery through which the rotating shaft is passed, and seals against the rotating primary sealing element
  • Equipment for mechanically loading- leads to the initialization of sealing by biassing the main sealing components in contact. These can be metal bellows or springs, including wave springs, multiple springs, and single springs.
  • Static and/or dynamic secondary seals – A mechanical seal that accounts for any shaft motion that could harm the seal faces are placed between the equipment shaft and housing and the mechanical seal parts.
  • Drive mechanisms –Examples of drive mechanisms used to deliver rotation to the rotating primary seal face include set screws and drive pins.


        Why do we use mechanical seals?


  • There is no “visible” leak, although seals do lose vapour as soon as the fluid coating on their faces touches the atmospheric side.
  • If it were trapped and condensed, this would amount to roughly 1/2 teaspoon each day at standard operating pressures and temperatures.
  • The shaft or sleeve of the pump is not harmed by contemporary cartridge seal designs.
  • Daily maintenance is decreased since seals feature internal springs that allow them to self-adjust as the faces deteriorate.
  • The lightly loaded faces of seals require less energy than gland packing.
  • As the lubricant is not impacted by seal leakage and washout, bearing contamination is reduced during normal operation.
  • If the product is contained in the pump, plant equipment is less susceptible to corrosion.
  • This method also allows for the sealing of the vacuum, which is problematic for packing because the air was sucked into the pump.
  • Even though water is an expensive resource, thus less product waste will result in financial savings, as will less cleanup of the region.



To learn more about how we can assist you in selecting the ideal mechanical seal for your needs, as well as other equipment, get in touch with Kemtron.ie right away.