Hi, I am new to the NFPA 291 code. Please I need some clarification on the fomula for discharge at specified residual pressure /calculating rated capacity at 20 psi (i.e. 188.8.131.52)
For instance: static = 100psi residual = 80 psi desired residual pressure = 20psi
To determine hr, which is correct?
1) hr = static pressure - desired residual pressure
100 - 20 = 80 psi
2) hr = residual pressure - desired residual pressure
80 - 20 = 60 psi