Who is actually supposed to use each hose connection — and why that answer, not the hose diameter, is what "class" really means.
Ask someone what separates a Class I standpipe from a Class II, and the answer that comes back is almost always about hose size — "Class I is the big one, Class II is the small one." That's true as far as it goes, but it skips the part that actually matters. NFPA 14 doesn't define these classes around hose diameter for its own sake. It defines them around a much more consequential question: who is this connection built for, and when are they expected to use it?Get that backwards, and the mistake isn't cosmetic — it's a life-safety design error.