Dry Sprinkler 2
Dry Sprinkler 2 : A sprinkler system having pressurized air (rather than water) in the distribution pipes until a heat-activated sprinkler head opens and releases the pressure, which opens a water valve (and possibly an accelerator valve) to flow water to the open head; used where the protected premises are not heated during freezing temperatures or where pressurized water in overhead sprinkler pipes could create another hazard