sprinklernotes
Pipe Size for a Hose Valve Located on the Roof
You have asked the following question: “What size piping and control valve are
required to supply a single 2½ in. hose connection on the roof to be installed
per Sections 7.3.2.9 and 7.3.2.9.2.1? Section 7.6.1 requires standpipes to be
at least 4 in. but Section 7.6.3 requires branch lines to be not smaller than
2½ in.” In response to your question, we have reviewed NFPA 14, 2016 edition as
the applicable standard. Our informal interpretation is the piping and control
valve for a roof hose connection are to be 4 in.
Even though this is not explicitly stated in Section 7.3.2.9, the piping and
control valve for a roof hose connection are still part of the main line and
are to be at least 4 in. This is stated in Section A.7.3.2.7 and shown in
Figure A.7.3.2.7. For vertical standpipes, branch lines are typically
horizontal piping from the vertical standpipe not serving more than one hose
connection. The purpose of a branch line on a vertical standpipe system is to
meet the travel distance requirement when it is not practical to install an
additional standpipe and can be covered by one additional hose connection. In
this instance the hose connection on the roof is not an additional hose
connection being installed to meet the travel distance requirement, thus the
piping and control valve are required to be at least 4 in.
