PTFE and EPDM Seal: What Is the Difference

What is PTFE Mechanical Seal

PTFE, also known by the brand name Teflon, is a synthetic fluoropolymer renowned for its exceptional chemical resistance and low friction coefficient. PTFE mechanical seals are made from this material, which has a wide operating temperature range from -320°F to 500°F (-196°C to 260°C). These seals are highly resistant to most chemicals, including strong acids, bases, and solvents.

Advantages of PTFE Mechanical Seal

• Exceptional chemical resistance: PTFE seals can withstand exposure to a wide range of aggressive chemicals without degradation.
• Low friction coefficient: The low friction properties of PTFE minimize wear and tear on the seal and mating surfaces, extending seal life.
• Wide temperature range: PTFE seals can operate effectively in both extremely low and high-temperature environments.
• Non-stick properties: PTFE’s non-stick nature prevents the buildup of contaminants on the seal surface, ensuring consistent performance.

Disadvantages of PTFE Mechanical Seal

• Limited elastic recovery: PTFE has poor elastic properties, which can result in leakage if the seal faces experience significant wear or misalignment.
• Susceptibility to creep: Under constant load and high temperatures, PTFE seals may exhibit creep, leading to a loss of sealing force over time.
• Higher cost: PTFE seals are generally more expensive compared to other seal materials due to the complex manufacturing process and raw material costs.

What is EPDM Mechanical Seal

EPDM is a synthetic rubber compound that offers excellent resistance to heat, ozone, and weathering. EPDM mechanical seals are known for their durability and versatility in various applications. These seals have an operating temperature range from -50°F to 300°F (-45°C to 149°C) and exhibit good resistance to mild acids, bases, and some solvents.

Advantages of EPDM Mechanical Seal

• Excellent weathering and ozone resistance: EPDM seals maintain their properties when exposed to outdoor conditions and ozone, making them suitable for applications in harsh environments.
• Good heat resistance: EPDM seals can withstand continuous exposure to high temperatures without significant degradation.
• Durability and long service life: The resilient nature of EPDM contributes to its durability and long service life in demanding applications.
• Cost-effective: Compared to PTFE seals, EPDM seals are generally more affordable, making them a cost-effective choice for many applications.

Disadvantages of EPDM Mechanical Seal

• Limited chemical resistance: EPDM seals are not recommended for use with strong acids, bases, or hydrocarbon solvents, as these chemicals can cause swelling or degradation of the material.
• Lower temperature range: EPDM seals have a more limited temperature range compared to PTFE seals, which can restrict their use in extreme temperature applications.
• Prone to abrasion: EPDM seals may exhibit lower resistance to abrasion compared to PTFE seals, which can lead to premature wear in applications with abrasive media.

When to Use PTFE Mechanical Seal

1. Highly aggressive chemicals, such as strong acids, bases, or solvents.
2. Extreme temperature conditions, both low and high.
3. Non-lubricated or dry running conditions, as PTFE’s low friction properties minimize wear.
4. Food, pharmaceutical, or other hygienic processing, as PTFE is FDA-compliant and resistant to bacterial growth.

When to Use EPDM Mechanical Seal

1. Exposure to weathering, ozone, or UV radiation.
2. Continuous high-temperature operation, within the specified range.
3. Mild acids, bases, or some solvents.
4. Cost-sensitive projects that require a durable and reliable sealing solution.