Mechanical Seals

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Mechanical seals are utilized when sealing between a rotating shaft and a vessel, such as a pump housing. They are made to keep liquids from entering or exiting a container while enabling the shank to move, allowing machinery to run smoothly and without interruption. The application, installation, and operation must be considered to ensure reliability when choosing a mechanical seal.

How Does A Mechanical Seal Work?

A mechanical seal consists of two flat faces, one rotating and one stationary, mounted perpendicular to the shaft. The rotation of the rotary seal ring against the stationary seal ring causes a rapid pressure drop across the primary seal interface caused by friction on the liquid molecules between the seal faces. Liquid molecules also act as miniature ball bearings to lubricate and reduce friction, reducing heat and wear.

Types of Mechanical Seals

Cartridge, component, and air are the three most widely utilized types of mechanical seals. The types differ in their design, structure, and distribution of the hydraulic forces on their faces.

Cartridge

A cartridge-mounted, end-face mechanical seal is a self-contained mechanism with sealing components, including a gland, sleeve, and hardware. A cartridge seal enables the manufacturer to preassemble and calibrate the unit. Installation and maintenance are simplified because the manufacturer handles these tasks. Cartridges may be supplied with either one or two seals, depending on the application’s needs.

Component

Component mechanical end-face seals consist of a rotating part and a stationary seal that mount to a gland or housing. Since they are not preset, maintenance and installation are more involved than cartridge seals, and installing them requires skilled professionals who can configure them effectively.

Air

Pneumatic, non-contacting air seals are used to seal rotating shafts. These seals are often used when dry powder or slurry is present. Product loss, emissions, and contamination are avoided by using small amounts of air or inert gas, and this air is restricted to provide positive pressure and an efficient seal.

Mechanical Seal Components

Most mechanical seals usually have 5 parts:

1. Rotating primary face. Fixed to and rotating with the shaft, this component seals against the stationary primary sealing element.
2. Stationary primary face. This part is attached to the stationary housing of the pump, mixer, or other apparatus where the rotating shaft travels and is sealed against the moving primary sealing component.
3. Mechanical loading devices. This mechanism presses primary sealing parts together and closes them. Single, multiple, wave or metal bellows can be used.
4. Static or dynamic secondary seals. These seals are used when there is motion between surfaces, serving as mechanical protection that adjusts on shaft movement that could harm the seal faces.
5. Drive mechanisms. These are set screws and driving pins to rotate the primary seal face.

Why Use Mechanical Seals?

Mechanical seals are preferred for most industrial applications, especially by pump manufacturers, as mechanical seals reduce fluid leaks better than other approaches. Among its many benefits includes:

• Efficient leakage prevention. Mechanical seals are perfect for procedures involving chemicals such as hydrochloric acid, sulfuric acid, and other hazardous substances.
• Component durability. Sleeves and shafts do not wear out quickly. Mechanical seals reduce preventive maintenance if well-installed and can ensure durable seals.
• High resistance. Mechanical seals can withstand higher speeds and pressure than traditional packing.
• Variety of designs. These seals come in various configurations to fit different pumps and machinery.

Durable & Effective Mechanical Seals By Mercer Gasket & Shim

Mercer Gasket & Shim offers a variety of high-performance mechanical seals that provide superior sealing capabilities in even the most demanding environments and conditions. Our practical and durable mechanical seals help reduce operational costs and improve production and system reliability.

We always aim to achieve 100% on-time delivery and 0% defects. We’re proud of our flexibility, 24-hour service, and 100 years of experience with specialized industrial products. Contact us today to learn more about our products and services.