Crimp Caps

What are Crimp Caps?

Crimp caps, also known as crimping caps, are used together with a rubber stopper or a septum, usually coated with PTFE, as part of the closure of a sample vial: with the aid of the crimp cap, the stopper or septum is attached to the neck of the vial. Unlike other caps, crimp caps are not screwed to the vial, but are attached using special crimping pliers. Caps with a septum made of rubber, butyl or silicone allow easy piercing with a syringe. Three-layer septa with a slot are frequently used in the HPLC sector, for example.

Successful analyses: choosing the right crimp cap

Depending on the application, crimp caps made of aluminum or magnetic caps made of bimetal can be used as closures. In addition to the correct size in relation to the sample bottle, the suitability of the cap for the respective autosampler in gas (GC) or liquid chromatographs (HPLC) is also decisive for the selection.

The choice of material for the piercing membrane also depends on the intended use. To prevent contamination of the sample by the support material, most septa are coated on the inside with an inert material such as PTFE. The support materials differ in terms of thickness, Shore hardness and purity. Common materials for the septum of a flared cap include silicone, natural rubber and butyl. Silicone, for example, has a high purity and can therefore be used for demanding analyses. Natural rubber has good resealing properties, which makes it particularly suitable for multiple injections. Septa made of butyl, on the other hand, have very good chemical properties.

The temperature resistance of the various materials should also be taken into account. For example, septa made of natural rubber can only be used in a range from -40 °C up to 120 °C, while silicone can be used at -60 °C up to 200 °C.

Correct use of crimp cap with septa

To avoid contamination of the sample material at all costs, septa coated with PTFE can be used. Similarly, the use of pre-slit septa can also prevent abrasion from entering the sample when piercing the substrate. Another problem can be the creation of a vacuum during sample collection. In this case, the use of pre-slit septa can also help, as the pressure can be better compensated with these

Order crimp caps for laboratory analytics online now

In our online store you will find a wide range of crimp caps for every application. In addition, we offer you an extensive selection of matching vials, crimping tools, septa, syringes and many other products for laboratory use. To make it easier for you to find the matching sample vials, some of our crimp caps are also available in a practical set with the corresponding vial.