Question: how to calculate bkw of fan?
Answer: Using the formula given in books using mmH2O as pressure.
Kw = (m3/sec x Pressure mmH2O) /102 = 16 x 500 /102 = 78.4 Kw.
Using the formula given by Ted as Watt = m3/sec x pressure (pa)
500 mmH2O = 500 x 9.8 = 4900 pascal.