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28 February 2014 Flammability test for sunglasses: developing a system
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Proceedings Volume 8930, Ophthalmic Technologies XXIV; 89301G (2014)
Event: SPIE BiOS, 2014, San Francisco, California, United States
Recent investigations show the need for certificating sunglasses to ensure the safety and health to population. The Brazilian Standard ABNT NBR 15111 regulates features to sunglasses, however, there is not a sunglasses certification office in Brazil, therefore, our lab has been developing several equipment for sunglasses testing. This work refers to one of them: the flammability test system for sunglasses in compliance with the NBR 15111. The standard provides requirements for the flammability test procedure which requires that the equipment must operate at a temperature of 650 °C ± 20 °C; the end of a steel rod of 300 mm length and 6 mm diameter should be heated and pressed over the surface of the lenses for five seconds; the flammability is checked by visual inspection. The furnace is made of ceramic. We used a power electronic circuit to control the power in the furnace using ON/OFF mode and for measuring the temperature, we used a K-type thermocouple. A stepper motor with pulley lifts the steel rod. The system reaches the working temperature in 15 minutes for a step input of 61 V in open loop system. The electronics control are under development in order to shorten the time necessary to reach the working temperature and maintain the temperature variation in the furnace within the limits imposed by the standard as next steps.
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Renan Magri and Liliane Ventura "Flammability test for sunglasses: developing a system", Proc. SPIE 8930, Ophthalmic Technologies XXIV, 89301G (28 February 2014);

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