What's the difference between a "dry" sprinkler system and a chemical sprinkler system?
I'm totally ignorant, so use small words, please!
Dry = filled with air until a head pops, at which time the "dry valve" opens and fills the previously dry system with water to suppress the fire. Typically used where wet systems would freeze like canopies, overhangs, attics, walk-in freezers and coolers, etc.
Chemical = chemical in lieu of water, typically used to not damage the area served as much as being covered in water would. Used frequently in data centers, high value libraries, sometimes museums, things like that.