Which class of standpipe system combines 1 ½" hose and 2 ½" outlets for simultaneous use?

The Class III Standpipe System is designed to meet the needs of both professional firefighters and building occupants. This system features both 1 ½-inch hose connections, which are intended for use by trained individuals, and 2 ½-inch outlets specifically for use by fire departments.

This design allows for simultaneous use of both sizes of hose, facilitating a more efficient response during firefighting operations. The presence of both outlet sizes is critical, as it allows firefighters to connect standard firefighting hoses while also providing the capability for occupants or trained staff to use a smaller hose for initial fire control if needed.

In contrast, a Class I system encompasses only the 2 ½-inch outlets for fire department use, making it unsuitable for occupant use. A Class II system includes only the 1 ½-inch hose connections for use by occupants, which does not provide the necessary capability for simultaneous operations as found in Class III systems. A proprietary alarm system, on the other hand, does not pertain to standpipe configurations but rather refers to specific alarm systems used in certain buildings. Thus, the correct understanding of Class III attributes leads to its designation for systems that cater to comprehensive usage.