Which class of standpipe is designated for use only by the fire department?

The class of standpipe designated for use only by the fire department is Class 1. This classification is specifically intended for firefighting operations and requires a 2.5-inch (65 mm) NST (National Standard Thread) coupling, allowing trained firefighting personnel to connect their hoses directly to the standpipe system.

Class 1 systems are designed to provide large volumes of water at high pressure, ideal for dealing with significant fire conditions. They are typically found in commercial buildings, high-rises, and other structures where firefighters need to supplement their equipment during emergencies.

In contrast, other classes of standpipes serve different purposes. Class 2 standpipes are intended for use by trained personnel—such as building occupants or staff—equipped with 1.5-inch (38 mm) hoses for smaller fires. Class 3 combines features of both Class 1 and Class 2, allowing for both firefighter and occupant use, equipped with both large and small hose connections. Class 4 standpipes generally do not exist in standard classifications within fire codes.