Mechanical seals with PTFE sealing rings: what are they?

Mechanical seals with PTFE sealing rings: what are they?

A focus on these types of seals with numerous advantages

Mechanical seals are essential components used in a wide range of industries to ensure tightness between moving mechanical parts. Their importance is such that without them, many industrial processes would be compromised, with both economic and environmental consequences. In this context, mechanical seals with PTFE rings stand out as an innovative and versatile solution, suitable for the most demanding industries.

With this article, we at Meccanotecnica Umbra will explore the secrets of these seals, the benefits they bring and their applications in industry.

Introduction to PTFE and its use as a material for mechanical seals

PTFE, or polytetrafluoroethylene, is a synthetic polymer formed from tetrafluoroethylene units, known for its outstanding chemical and physical properties. This material can withstand extremely high temperatures without decomposing, operating effectively in the range from about -200°C to +260°C. In addition, PTFE is highly resistant to corrosion and chemical reactivity, making it ideal for use in chemically aggressive environments.

Because of its extremely low coefficient of friction, it is an excellent material for sealing rings. In addition, it is an excellent electrical insulator and has high resistance to water and moisture, qualities that contribute to its nonstick properties.

In this context, we at Meccanotecnica Umbra have developed our own version of PTFE, called Mecflon®, enriched with carbon or glass fibers to increase physical and mechanical performance.

Therefore, due to its excellent chemical and physical properties, PTFE is used in the following components of a mechanical seal:

  • Sealing rings: PTFE sealing rings are used to prevent leakage of fluids (liquid or gas) between relative moving surfaces, such as rotating shafts or pistons, in industrial and household applications.
  • Coatings and inserts: PTFE is often used as a coating or insert in seals to improve chemical resistance and friction reduction properties.
  • Compression seals: in high-pressure applications, PTFE can be used to create compression seals that deform to fit the sealing surfaces, allowing a tight seal.
  • Pump seals: PTFE seals are used in pumps to prevent fluid leakage because of their chemical resistance and ability to operate at high temperatures.

Advantages of mechanical seals with PTFE rings

Mechanical seals with PTFE rings, due to their properties, offer numerous advantages over other types of materials.

PTFE is extremely resistant to most chemicals, including strong acids, bases, solvents and oils. In addition, PTFE's low coefficient of friction reduces wear and improves efficiency in mechanical systems.

These rings can operate over a wide temperature range, from about -200°C to +260°C, making them suitable for both cryogenic and high-temperature applications.

Despite being a relatively soft material, PTFE forms a lubricating film that reduces wear and extends the operating life of seals.

PTFE's excellent non-stick properties prevent the accumulation of residue and facilitate cleaning and maintenance of seals. Finally, PTFE's flexibility and ability to conform to uneven surfaces ensure an effective seal by compensating for small imperfections.

Disadvantages of mechanical seals with PTFE rings

Despite their many advantages, mechanical seals with PTFE rings have some disadvantages that must be considered in mechanical applications.

PTFE has relatively low mechanical strength and can deform under high loads, which can lead to seal leakage in high-pressure applications. In addition, PTFE has a relatively high coefficient of thermal expansion; under changing temperature conditions, it can expand or contract significantly, affecting the effectiveness of the seal.

Mechanical seals with PTFE rings are more difficult to install than other materials because of their stiffness and tendency to deform, requiring specific installation techniques to avoid damage.

The cost of PTFE is higher than other seal materials, affecting the total cost of the mechanical system. Finally, in applications with high dynamic loads, PTFE may not be the ideal choice because of its tendency to deform and low mechanical strength.

Application fields of mechanical seals with PTFE rings

Mechanical seals with PTFE rings find use in a wide range of industries due to their excellent chemical, thermal and low-friction properties.

In the chemical and petrochemical industries, PTFE seals are ideal for applications involving aggressive chemicals, acids, bases and solvents, being used in chemical reactors, pumps, valves and heat exchangers.

In the food and pharmaceutical industries, PTFE seals, due to their chemical inertness and biocompatibility, are used in food and pharmaceutical production machinery, where avoiding contamination is essential. Also, in household applications, PTFE, and particularly Mecflon®, is used in mechanical seals mounted on the operating pumps of both industrial and civil dishwashers, ensuring efficiency and reliability.

Final considerations and the role of Meccanotecnica Umbra

In conclusion, mechanical seals with PTFE rings are an optimal choice for multiple industrial applications, offering state-of-the-art sealing solutions in environments that present extreme challenges in terms of temperature, pressure and exposure to aggressive chemicals.

In this scenario, we at Meccanotecnica Umbra offer a range of PTFE products specifically for the home appliance sector, but upon request we can provide products designed under specific customer requirements, which use sealing rings with "grade Mecflon®". Contact us now for more information!

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