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Pawling Engineered Products

Engineered Elastomeric Technologies for Sealing, Clamping, Actuating

Septa

Rubber Septa

By definition, a rubber septum consists of a disk of rubber or similar material used to seal a vial or other device. It is installed along the inside of a cap, which is typically made of metal or plastic. A syringe needle pierces the rubber septum for the purpose of injection and, on withdrawal, the elasticity of the septum ensures that the hole reseals.

Rubber septa are most commonly used to seal medicinal vials containing either a liquid or freeze-dried solid (which is then liquefied in water or other substance). The medicine is drawn from the vial using a needle, then injected. Septa may also be used when a substance either needs to be injected into or pulled from a vial (or other device) then re-sealed. An injection port on a gas chromatograph is a good example. Other uses include but are not limited to:

  • Rubber septa to seal vials used to store samples in a lab. These vials are typically used in conjunction with either a gas or liquid chromatograph.
  • Sealing the injection port on top of a gas chromatograph. These injection port septa are meant to seal the entire chromatographic column.
  • Sealing test ports on chemical or pharmaceutical processing equipment. When samples need to be taken in a closed system, use of an injection port septum may be a good way to insert a needle to take a sample without having to shut the entire system down.

Rubber septum design varies widely depending on the application. Medicinal vial septa are typically compression molded out of Silicone or Butyl rubber in multi-cavity molds within a high controlled manufacturing environment. Other septum types may include a chemical barrier layer, most commonly PTFE, or in extreme case, two barrier layers. These designs are most often punched from a sheet of rubber.

The quality of the barrier film and rubber are extremely important for many reasons. A poor quality septum may lead to improper re-sealing, skewed test results, or poor quality product. To minimize this, manufacturing inputs must be strictly controlled.

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