What type of valve is typically used in a class II standpipe?

In a Class II standpipe system, which is designed primarily for use by trained personnel, the typical valve size is 1.5 inches. This size is optimal as it accommodates the hose connections used by firefighters or other responders who are trained to operate the standpipe system.

Class II standpipes are intended for use with smaller diameter hoses suitable for interior firefighting operations, particularly in commercial or multi-story buildings where the fire may be managed more effectively with hand-lines of this size. The 1.5-inch valve provides a balance of flow and pressure that is vital for quick response without causing undue strain on the firefighters using it.

The other valve sizes, such as 2.5 inches, 3 inches, and 4 inches, are typically found in Class I or Class III systems, where larger flow rates are needed or intended for use by fire department personnel or large hoses. However, for Class II systems, the 1.5-inch valve is the standard choice due to its practicality and efficiency for the intended user group.