Class I Systems
Class I Systems [2-1/2" (64mm) hose connections] are provided for use by fire departments and those trained in handling heavy water streams. In high rise buildings without sprinklers and beyond the reach of fire department ladders, Class I systems provide water supply for the primary means of fire fighting, i.e. manually.
Class II Systems
Class II Systems [1-1/2" (38mm) hose lines] are provided for use by trained building occupants until the fire department arrives.
Class III Systems
Class III Systems shall provide [1-1/2" (38mm)] hose stations to supply water for use by trained building occupants and [2-1/2" (64mm)] hose connections to supply a larger volume of water for use by fire departments and those trained in handling heavy water streams.