Making Big Connections in a Historically Small World

Fire Department Connections (FDCs) have been around a lot longer than large diameter hose (LDH)… and while many departments have adopted LDH for use on the fireground, many — if not most — FDCs remain 2.5-inch in size.

Fire department connectionOften, one 2.5-inch “snoot” is present for each ~250 GPM of flow a system is expected, but in some jurisdictions, an FDC may augment connections with a single large-diameter connection.  These are either integrated into the standpipe (say, on either end of a “T” header) or as a separate pipe, as seen here.

During a typical five-year test, there isn’t a requirement to flow one over the other, or even both — subject to the local Agency Having Jurisdiction (AHJ)’s say so, of course — but on new construction sign-off, it’s more of a need… and five-year tests aside, some do require both the 2.5-inch and large diameter connections be flowed.

But to be practical: some fire engines do not have a 5-inch discharge.  (Newer apparatus do, but that’s not a universal truth.)  To overcome this, we’ve adopted, we’ve found an appliance to marry a series of 2.5-inch hoses into a 5-inch supply line is a decent solution.  (And yes, in areas where we’ve found 5-inch FDCs and we work on new construction tests, we are carrying this gear, too.)

And check on the math: four times a 2.5-inch hose equals the same volume as a 5-inch hose.  While there may be some friction loss in the four lengths of smaller hose (and in the manifold as well) that is greater than the typical 5-inch hose lay from the engine’s discharge right into the FDC, it’s far closer to the alternative of adapting up from a single, double or even triple 2.5-inch hose connection into the same discharge point.



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