Optical Ignition
Paper ignites at 240 degrees Celsius
Did you know that incandescent lightbulbs can reach 100 degrees Celsius or more? They can heat paper to temperatures beyond 200 degrees, if placed carelessly. The filament temperature can become exponentially hotter than that, with temperatures in excess of 1000 degrees Celsius. No wonder they cause fires.
After my kids told me that, my next thought was LED fixtures. I already knew that fluorescents emit 30% of their energy as heat, reaching temperatures higher than 85 Degrees C. A bottle of watercan reach 121 degrees in the sunlight, and as a lens can heat elements to past 400 C. Even LED fixtures can emit heat over 60 degrees Celsius. After just a little reflection, I knew I was right to be worried. All of those fixtures are potentially dangerous.
Can you see the solution?
That was the question I asked myself through the whole engineering process. Could I see a new method of making our fixtures safer? After a discussion with our staff we came up with new characteristics. The European Committee for Electrotechnical Standardization and the International Electrotechnical Commission proposed safe radiation limits of between 35mW and 5mW/mm2. We wanted to be much more conservative than that, so we chose the more conservative limits of 5 mW/mm2. That was the solution, a radiant power that met those guidelines.
A Fascinating Engineering Challenge
However, balancing light output and ignition reduction was very challenging. When we started planning, we realized that an explosion needed three parts. One element to absorb the light, a radiation source, and the presence of explosive gas. After some deliberation our team chose to focus on the most immediate danger, dirt or other debris on the surface of the fixture. In fact, we have seen insect bodies that had burned through fixture enclosure. We absolutely needed to fix this problem, and soon.
The hairs on a fly
After months of hard work, we ended up with a new design specification. First, we used secondary optics to spread light to under 5mW/mm2. Next max drive power was limited to around 190 watts, ensuing light output was not excessive. Last, our heat sinks maximize heat transfer, nearly eliminating any possibility of ignition.
Testing was initiated on a fly, a common and troublesome elements near many fixtures. We started the experiment, and three days later we had some interesting results. The fly had suffered no damage. The hairs, the wings, and the eyes were all still undamaged. Together with my team, we solved the problem! We had an Ultra Safe Hazardous Locations fixture!
XCANLED Fixtures
As we have shown our XCANLED Fixture is more than safe for hazardous locations. With its maximum output of 5 mW/mm2, it is highly unlikely to ignite anything in front of it, even if it is stuck to the lens. With the fixtures on board thermal management, it is rated for over 60,000 hours lifetime use. In addition, it is IP66 certified and so very well suited for very harsh conditions.
This product has already been installed in many hazardous locations without incident. We have fixtures in rocket testing facilities, on the tops of mountains, and in military applications.
