Required Delivered Density

 

Required delivered density (RDD) is the minimum rate of water application that, if delivered to the top of the fuel package, is capable of providing early suppression.

Suppression can be considered to occur when the heat release rate of the fire is quickly knocked down and is prevented from resurging.

Actual delivered density (ADD) is the actual rate of water application that a particular configuration of flowing sprinklers is capable of delivering to the top of a fuel package, depending on the strength of the upward fire plume.