What size hose connection is standard for a Class II standpipe system?

The standard size for hose connections in a Class II standpipe system is 1.5 inches. This choice reflects the design intent of Class II systems, which are primarily intended for use by trained personnel to combat fires in commercial and institutional buildings. The 1.5-inch size strikes a balance between ease of handling and sufficient flow capacity to effectively deliver water to combat fires.

Class II systems are generally equipped with hoses that allow for direct use by fire departments or trained building staff, and the 1.5-inch connection ensures that water can be delivered at adequate pressure while remaining manageable for users.