Every equation RiserSheet uses, written out. There is no chat widget and no support portal; there is an address at the bottom of this page that a person reads.
p = 4.52 · Q^1.85 / (C^1.85 · d^4.87)
Multiply by the total length, physical run plus fitting equivalent length, to get the loss across the pipe.
q = K · √p
Reversed, p = (q / K)². K is a US customary quantity; a metric K for the same orifice is a different number.
v = 0.4085 · Q / d²
Reported as an advisory. NFPA 13 sets no velocity limit for sprinkler piping.
p = 0.433 · h
Water climbing loses pressure and water dropping gains it. The inverse is 2.31 ft per psi.
p(Q) = p_static − (p_static − p_residual) · (Q / Q_test)^1.85
Plotted on a Q^1.85 axis this is a straight line, which is why reports use that scale.
q_min = density · coverage
The pressure that flow requires follows from p = (q_min / K)². The larger of that and the 7 psi floor governs.
L_eq = L_table · (C / 120)^1.85
RiserSheet uses the printed multipliers where NFPA 13 gives them and this expression otherwise.
The arithmetic, and showing its work. The designer of record stays responsible for the inputs, for the code edition the authority having jurisdiction has adopted, and for field verification. Every report carries that statement, and the validation page sets out how the solver is checked.
Write to [email protected]. If you have found a number you believe is wrong, send the inputs that produced it — that is the most useful message this address can receive.