Applicable standard test methods include:
- ASTM D2063, "The torque retention of continuous thread closures on containers, with matching finishes, for predetermined environmental conditions over time"
- ASTM D3198, "Standard Test Method for Application and Removal Torque of Threaded or Lug-Style Closures".
For precision applications, such as syringe Luer fittings, the Mecmesin Helixa torque system is used in conjunction with data acquisition software. In addition to providing a motorised application, its counterbalancing mechanism allows the removal of axial force, whilst enabling the application of a precise top load when required.
Leak resistance of closures
Closures applied to nominal application torque are routinely tested for resistance to leakage after storage at elevated temperature, simulated transit vibration or vacuum testing as detailed in ASTM D4991 "The testing of empty containers for resistance to leakage under differential pressure conditions such as those which can occur during air transport".
The causes of leakage can be investigated by dimensional analysis of the container and closure thread dimensions with the aid of a non-contact optical measuring stage.
Sports closure testing (BSDA Code of Practice)
The BSDA "Code of Practice for Sports Closures" sets out the tests needed to demonstrate due diligence for sports closures.
Smithers is able to test closures to all aspects of the code, including the rotational opening force test which was developed for push-pull closures by Smithers (see rig).
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