Set the freezer to the required sub-zero test temperature and wait for it to reach that point.
Punch out a rubber test specimen of the required size and shape, using the punch press and specimen dies.
Seal the specimen in the plastic wrap of zip-top bag to keep out moisture and place it in the freezer. Allow the specimen to sit in the freezer for at least three to four hours to make sure it's cooled to the test temperature.
Prepare and calibrate the moving cross-head apparatus. Connect the pneumatic grips to a compressed air line and connect the conditioning chamber to a carbon dioxide cylinder. Start up the data-acquisition software and prepare for measurement. Input sample dimensions into the computer as well as any required software parameters.
Set the conditioning chamber to the required sub-zero test temperature. Allow carbon dioxide to cycle into the chamber until it reaches the desired temperature.
Remove the test specimen from the freezer and take it out of the plastic wrap. Quickly open the conditioning chamber door and fix each end of the specimen in the pneumatic grips. Close the chamber door and wait several minutes for it to cool to the test temperature.
Activate the apparatus so the grips move apart and the device records the grip travel distance until the specimen breaks. Read off the percent elongation of the specimen at the test temperature from the attached computer.