Which type of standpipe is indicated by a 2 1/2 inch outlet without hose?

The type of standpipe indicated by a 2 1/2 inch outlet without hose corresponds to a Type 1 Standpipe. This type is designed primarily for use by trained firefighting personnel, as it provides a connection point for fire department hoses to be hooked up directly at the outlet.

Type 1 Standpipes are essential in high-rise buildings and other structures where access to fire service connections must be efficient and powerful enough to suppress fire effectively. The 2 1/2 inch size is a standard connection used by fire departments, allowing for a substantial water flow necessary during firefighting operations.

In contrast, other types of standpipes differ in design and function. For example, Type 2 Standpipes might include a hose connection for use by building occupants, while Type 3 and Type 4 Standpipes serve different purposes and configurations, which do not match the specification of having a 2 1/2 inch outlet without hose. Therefore, the attributes of a Type 1 Standpipe are integral in facilitating a rapid and effective firefighting response.