Security cap for gas cylinders

There have been many innovative ways in which polymers have been used to create new designs fulfilling unexpected funetions, such as the development 

However, whole batches were found to be failing at the critical hinges when held in storage, and had to be returned to the moulders for scrapping. Indeed, the warehouse at the factory was full of rejected products, a sight 

13 Security cap before fitment showing hinges (HH) and gates (arrows). 

Of sixteen samples tested, only five survived fitment to the oxygen cylinder (Fig. 10.12). The remainder showed splits or cracks in the hinges. A quantitative test was needed to test the strength of the guards, and close attention to moulding conditions was required. 

A simple objective test was required to mimic the needs of the end user and yet be easily applied in the factory. To develop the test, a mole wrench and 

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