How do fire sprinklers work?
Answer – At each sprinkler, the water under pressure in the pipe is held back by a plug held in place either by metal parts or a small glass vial filled with fluid. When sufficient heat hits a sprinkler, the special solder holding the metal parts together melts, or the fluid in the glass vial expands enough to break the glass. In either case, the plug is released and the water begins to flow.
