Standpipe systems can be either wet or dry sys-tems and are broken down into four types,
1. A wet standpipe system that has water through-out the system at all times. When an outlet is opened, water immediately begins to ﬂow.
2. A dry standpipe system that is under no air pressure, much like a deluge-type sprinkler system. It must be activated by manual oper-ation of a valve at the beginning of the system or by a remote control located at each stand-pipe outlet.
3. A dry standpipe system that is ﬁlled with air under pressure, much like a dry sprin-kler system. When a standpipe connection is opened, air is allowed to escape the system while water enters.
4. A dry standpipe system that has no water supply. Water must be supplied by the ﬁre department.