ELI5 Fire Extinguishers - why are they red in color?

Explain Like I'm 5: Bite sized answers to stuff you should know about - in a mini podcast by ELI5 Explain Like I'm Five Podcast

Why is most fire equipment red in color? What happens if you use the wrong class of extinguisher on a grease or metal fire? Could the future of firefighting be a "dubstep cannon" that uses sound waves to kill flames? ......View more