Using the Insurance Services Office $($ISO$)$ method, estimate the needed fire flow $($NFF$)$ in gallons per

minute $($GPM$)$ for a building described as follows:

The building $($construction class $5)$ comprises three floors, with floor areas measuring $4,000f{t}^2,$

$3,500f{t}^2,$ and $3,000f{t}^2,$ respectively.

The building is used for pharmaceutical retail sales and storage.

All vertical openings in the building have $1\mathrm{.}0$ hour or more protection.

All the doors are self$-$closing and labeled as class B fire doors.

The building's distance to the exposed building is $18$ ft $.$

The building's facing wall to the exposed building is masonry with semi$-$protected openings.

The length$-$height value $($i$.$e$.,$ length of the wall in feet times height in stories$)$ of facing wall of

exposed building is $475.$

The passageway openings are enclosed with a length of $15$ ft $.$

Single class B fire doors are installed at each end of the passageway.