Product Spotlight - Septas & Septa Lined Caps

Septa liners are typically composed of rubber, PTFE, silicone, Teflon, or a mixture of these materials. The construction of septa liners allows for the liner to reseal itself after being pierced by needles to extract liquids for sampling, chormatography, and other laboratory applications. Differences in thickness and bleed levels are important to consider when choosing the right septa liner. Bleed grades assist in the vigorous levels of testing to be performed with the test tubes and septa liners. Low bleed septa liners are suitable for multiple punctures and rigorous testing, while the ultra low bleed septa liners are formed to withstand gas chromatography. Differences in thickness determine the piercing ability of the liners. The larger size liners have a greater stiffness than the smaller sizes, which are thinner to allow needles pierce with less resistance.


SKS Science offers red septa liners, sold separately for installation to the top of test tubes under the caps chosen for use. The red septa liners are 11 mm in size with guiding holes in the center. These septa liners are composed of 100% pure premium silicone rubber, allowing for precise gas chromatography testing. During manufacturing, the average number of injections is 450 before any deterioration, and temperature uses up to 400° C. These liners are shipped in cases of 50 with each liner inside of a clear glass jar topped with a white plastic ribbed cap. Glass jars will eliminate contamination while storing, and clearly displays the number of septa liners remaining.

Clear snap caps in the 11 mm size offer two liner choices: orange silicone septa liners or red PTFE coatings over white silicone septa liners. Both options have a 1 mm thickness and eliminate the need of crimpers and decappers by snapping onto the test tubes. Another 11 mm size option is the clear polypropylene snap cap with Teflon septa liners. The Teflon septa liners are .254 mm thick with a broader septa liner opening on the top for quick, accessible draws. These liners are compatible with plastic or glass high recovery vials. Black phenolic caps with butyl septa liners, compatible with clear and amber glass media bottles, offer low permeability and have been used favorably with ketones and acids. The butyl construction allows for longer injection use with low deterioration. In a variety of sizes, plastic caps with PTFE coated silicone septa liners are available with 8/425 up to 24/414 neck finishes, and include caps in white, blue, and black colors with a variety of septa liners. In the 8/425 and 10/425 sizes, the septa thickness is 1.5 mm, and the 24/414 septa liners have a 3 mm thickness to serve large openings with high stiffness over long periods of time. The 9 mm size is a snap style cap and the remaining sizes are threaded to screw on the top of test tubes, vials, or media bottles.


Aluminum crimp caps, applied with crimpers and removed by decappers, in an 11 mm size include 1 mm thick septa liners composed of orange silicone with clear FEP coatings. The clear FEP coating is a variation of Teflon that provides additional chemical resistance and superior electrical properties. The 20 mm size aluminum crimp caps have a beige PTFE coat and white low bleed silicone septa liners with a 3 mm thickness. SKS Science offers a range of crimpers and decappers that are manual or automatic with additional features to match the processing requirements including speed, the number of test tubes per testing schedule, and frequency of testing.