While looking out at a lake or ocean, you may well note there are “not a lot of fires there”. When was the last time you read about arson crime in the Pacific? Exactly.
But despite water’s ability to put out fire, it is possible – if you try hard enough – to light a fire from within it. In fact, it is perfectly possible to perform welding chores while scuba diving.
To create a fire, all you need are fuel, oxygen, and heat. In combustion, a fuel and oxygen are converted into water (in the form of vapor) and carbon dioxide. It is this that makes it hot.
“Many believe it’s the breaking of chemical bonds in the fuel that produces heat. But it’s actually the opposite. When we break any chemical bond, heat is absorbed. It’s making new chemical bonds that releases heat – the creation of water vapour and carbon dioxide,” Jason Dutton, Professor of Chemistry at La Trobe University, explains in a piece for The Conversation.
“These newly formed bonds are stronger than the bonds in the […] fuel, meaning heat is released overall. So much heat that pyrolysis is sustained, consuming more fuel and spreading the fire.”
While “going underwater” seems like a great way to remove oxygen and heat, it is still possible to create underwater fire if you try hard enough.
People who tried hard enough.
When welding underwater, there are a few options. The first is to seal a hyperbaric chamber around the area that needs to be welded, creating a dry atmosphere for welders to work in. While this makes the job easier, and the results more reliable, sometimes a repair needs to be done urgently. In these circumstances, trained divers (and welders) may perform a wet weld.
“Wet welding relies on the release of gaseous bubbles around an electric arc to shield the weld and prevent any electricity being conducted through the water. This insulating layer of bubbles protects the diver but also obscures the welding area, making it harder to complete the weld correctly,” The Welding Institute explains in a blog post.
Though it will do in a pinch, it is far from ideal.
“The bubbles can also disturb the welding pool and the welded joint may cool too quickly due to heat dissipating through the surrounding water,” they continue. “This increases the risk of defects such as cracking.”
Fire is quickly quenched by the water, but it is nonetheless possible to produce a little fire underneath the sea.
Source Link: How Is It Possible To Create Fire Underwater?