ten-year-old veterinary syringe worker tell you that the factor of influencing the sealing of the veterinary syringe

The sealing is very important for veterinary prefilled syringe,because the syringe need store the medicine.So how do the veterinary syringe ensure the sealing?
The very syringe control the sealing by the following ways:

1. use the international standard sealing part
2. test the sealing when the syringe leave factory
3. test syringe,this syringe must conform to bacterial invasion test requirements and saturated brine test requirements
4. do acceleration test to ensure the sealing can satisfy usage requirements in shelf life