PTFE Silicone Septa

Polytetrafluoroethylene (PTFE) silicone septa are vital components in laboratory and industrial settings, combining the unique chemical resistance of PTFE with the flexibility and durability of silicone. These specialized seals play a crucial role in ensuring airtight, leak-proof closures in analytical instruments, especially in chromatography applications. Their robust design allows them to withstand harsh chemicals and repeated use, making them indispensable for maintaining sample integrity and accuracy in precise scientific measurements.

What is PTFE and what is it used for?

PTFE is a synthetic fluoropolymer of tetrafluoroethylene. It was accidentally discovered in 1938 by a chemist at DuPont who was trying to create a new refrigerant. After its discovery, it was found to be useful in cookware — as a non-stick coating. Currently, it continues to have applications across a wide range of industries and commercial appliances, including gasket material, caps and seals, tubing and membranes, and insulation material in the electrical and aerospace industries.

What are the benefits of PTFE?

The properties PTFE holds makes it uniquely suited to be a one-size-fits all solution to many industrial needs. These are a few of its most notable properties:

PTFE is known for its extreme chemical resistance. It’s resistant to almost all organic and inorganic chemicals — including acids, bases, and solvents. This makes it an ideal choice for use in chemical processing equipment, as well as in the production of chemical-resistant coatings and linings.
PTFE has a melting point of around 327°C (621°F), which makes it suitable for use in high-temperature applications. It also has good thermal stability, which means it can withstand repeated exposure to high temperatures without degrading or breaking down.

PTFE has a very low coefficient of friction, which makes it an ideal material for use in applications where parts need to slide against each other without generating heat or wear. This property also makes it a top choice for use in bearings, seals, and other components that require a low-friction surface.
PTFE is a non-stick material, which is why it’s frequently used to coat cookware and other applications where sticking or adhesion could be an issue.
PTFE is an excellent electrical insulator, which makes it favorable for use in high-voltage electrical applications, including wiring, cables, and connectors.

What are PTFE silicone septa and what are they used for?

PTFE silicone septa are specialized seals made from the layering of PTFE and silicone, the versatility of which makes them a formidable material, and especially useful in laboratories and other demanding analytical environments. More specifically, PTFE silicone septa are used in different forms of chromatography — that is, liquid and gas chromatography. They provide a reliable, leak-free layer between a sample container and the injection port of an analytical instrument. Designed to withstand repeated use and exposure to harsh elements, PTFE silicone septa retain their sealing properties for quite a long time. The PTFE layer of the septa provides chemical resistance, low extractables, and low particle shedding; while the silicone layer adds strength and durability to the seal. PTFE silicone septa are an essential component of laboratory and analytical equipment, providing a critical seal that ensures the accuracy and reliability of experiment results.

How To Choose the Right Septa

Choosing the right septa is important for reliable performance and longevity in laboratory and industrial applications. Several factors influence septa selection, including chemical compatibility, temperature resistance, durability, and the specific analytical technique used.

A durable septa should provide a strong, leak-proof seal while withstanding repeated punctures from needles without compromising its integrity. The chemical resistance of the PTFE layer is essential for preventing contamination or degradation, especially when working with aggressive solvents or reactive compounds. Temperature tolerance also plays a large role, as septa must maintain their sealing properties under varying thermal conditions.

In addition to material properties, the physical dimensions and compatibility with your instrument’s sample containers are key considerations. Selecting septa that are specifically designed for your application will reduce sample loss, improve reproducibility, and protect sensitive equipment.

For more information, consult ILT’s septa selection guide. This resource provides details on ILT’s production testing and quality standards to help labs select the right septa.