meaning of dry riser
A dry riser is a main vertical pipe intended to distribute water to multiple levels of a building or structure as a component of the fire suppression systems. The pipe is maintained empty of water. The dry riser is the opposite of a wet riser or wet standpipe system where the pipes are kept full of water for manual or automatic fire fighting operations. Dry risers have to allow access to a fire engine within 18 m of the dry riser inlet box.