vials are available in three closure types:crimp,snap,and screw cap.Each closure its advantages.

Crimp caps squeeze the septum between the rim of the gless vial and the crimped aluminum cap.This forms an excellent seal preventing evaporation.The septa stays seated piercing by the autosampler needle.The crimp cap vial requires crimping tools to carry out the sealing process.For few samples,manual crimper tools are the best choice.For large mumbers of sample,automated crimpers are available.

Snap caps are an extentsion of the crimp system of sealing.A plastic cap is stretched over the rim of the vial to form a seal by squeezing the septum between the glass and the stretched plastic cap.The plastic cap creates tension when trying to return to its original sizes.This tension forms the seal between glass,cap and septum. Plastic snap caps do not require any tools to assemble.

Snap caps are not as effcctive a seal as other closures.

If the fit of cap id very tingt,the cap ios hard to apply and may be subject to crack.

If the fit is too loose,the seal is poor and septum may dislodge.

Screw caps are universal.Screwing the cap applies a mechanical force that squeezes the septum between the glass rim and the cap.Screw caps form an excellent seal and mechanically hold the septum in place during piercing.No tools are required for assembly.