Mechanical Seal

In modern industry, mechanical seal, as an important sealing technology, is widely used in equipment such as pumps, compressors and mixers. Its main function is to prevent fluid leakage and protect the normal operation of equipment. With the continuous progress of science and technology, the design and materials of mechanical seals are also constantly developing to meet the needs of different industrial fields.

What is a mechanical seal?

A mechanical seal is a device used to prevent the leakage of liquids or gases and is commonly used in rotating machinery such as pumps, compressors and agitators. It forms a seal between a rotating shaft and a stationary part by means of a close fit between a static ring and a dynamic ring. Mechanical seals usually consist of several components, including springs, O-rings and sealing rings, and are suitable for high-pressure, high-speed, corrosive or abrasive working environments, offering the advantages of durability and stability.

The Importance of Mechanical Seals

Mainly because it can effectively prevent liquids or gases from leaking in rotating equipment, especially in the case of high pressure, high temperature or corrosive media. Compared with traditional packing seals, mechanical seals can provide more efficient sealing performance, reduce friction and wear, and extend equipment life.

Main Types of Mechanical Seals

• Single face seal: Suitable for general conditions, only one sealing face in contact with rotating equipment, widely used.
• Double face seal: Two sealing faces, suitable for high pressure, corrosive or toxic media environments, providing additional protection.
• Balanced seals: Reduced pressure on the sealing faces, suitable for high pressure systems, reducing wear.
• Non-equilibrium seal: Used in low-pressure systems, simple structure but limited scope of application.

Components of Mechanical Seals

Mechanical seals consist of a number of key components, each of which has a specific role to play in ensuring their sealing effectiveness:
Spring: Provides constant pressure on the seal, ensuring that the dynamic and static rings are in close contact, even in the event of wear or vibration.
O-Ring: acts as an elastic seal, preventing leakage of the medium through the gap in the seal and at the same time allowing relative movement between the dynamic and static rings.
Sealing rings (dynamic and static rings): the core component of the seal, the dynamic ring rotates with the shaft, the static ring remains motionless and the two ring surfaces are in close contact to form a seal.

Application Areas of Mechanical Seals

1. Pumps: Centrifugal pumps, screw pumps, etc. used for transferring liquids.
2. Compressors: Used for sealing gas in gas compressors.
3. Stirrers: Stirring equipment in the chemical and pharmaceutical industries.
4. Turbines: In turbine equipment used in the power and energy sector.
5. Petrochemical: Handling of high temperature, high pressure and corrosive media.

Choosing The Right Mechanical Seal

1. Centrifugal pumps

• Applications: Commonly used to transfer clear water or low viscosity liquids.
• Seal selection: Usually use single-end seal. Material selection should take into account the nature of the liquid (e.g. corrosive), and materials such as fluoroelastomer or carbon can be used. It is necessary to ensure that the sealing ring and the pump shaft with precision to prevent leakage.

2. Diaphragm pumps

• Application: Diaphragm pumps suitable for conveying liquids containing particles or viscous media.
• Seal selection: Since the medium does not directly contact the mechanical seal, a simpler form of seal can usually be selected. Use suitable diaphragm materials (e.g. PTFE, rubber) to improve corrosion and wear resistance.

3. Screw pumps

• Applications: For liquids with high viscosity and high solids content.
• Seal Selection: Double-ended seals are suitable to ensure stability under high pressure and high viscosity conditions. Seal material should have high wear resistance and high temperature resistance.

4. Chemical pumps

• Application: Chemical pumps for the transfer of chemical media, which may be corrosive or toxic.
• Seal selection: Double-ended seals are mostly used to provide additional safety. Material selection takes into account the chemical properties of the medium, and advanced corrosion-resistant materials (e.g. ceramics, PTFE, etc.) are usually used.

5. Electromagnetic diaphragm pumps

• Application: EODD diaphragm pumps used for conveying chemical liquids or where absolute sealing is required.
• Seal Selection: Since electromagnetic diaphragm pumps are usually of leak-free design, the sealing requirements are relatively low, but chemical-resistant materials are still required. Select high quality diaphragms to ensure sealing performance and service life.

Differences Between Gaskets And Seals

Washers: Usually placed between the bolts, nuts, flat ring, mainly used to spread the load, to prevent friction, loosening or leakage, mainly by mechanical means.

Seals: Used to prevent leakage of liquids or gases in equipment, often used between rotating or stationary parts. Seals rely on the elasticity of the material and the sealing surface of the close fit to prevent the flow of media.

Summary

Mechanical seals play a vital role in ensuring the efficient and safe operation of equipment. By properly selecting and maintaining mechanical seals, not only can leakage and contamination be reduced, but operating costs and downtime can also be significantly reduced.

AOBL, as a pump manufacturer, utilizes high quality mechanical seals in its pump products to minimize leakage rates, reduce maintenance costs and increase efficiency. Feel free to contact us to develop an outstanding solution for you.