The NFPA 24-Edition 2013 allows that the auxiliary valve ( Control Valve) be installed within 20 feet of the hydrant as per subsection 184.108.40.206.1.
Most the control valves that I have seen, were installed in the vicinity of the hydrant between 2 to max. 5 feet. I knew the NFPA said "within" that is inclusive, but I am looking for the situation that makes it to be installed in a way far.
What is the rationale behind this NFPA requirement?
My common sense told me that is due to accommodating the unexpected situation ( topography of the site, soil strength layers, etc.)
I do appreciate to have your opinion in this regard.