How to Calculate the loss of a circuit?
The pressure loss of a circuit is the addition of the pressure loss of each device in the circuit and all the obstacles met by the air.
Devices & equipment: the value of the pressure loss should be given by the supplier/manufacturer (ex: filter, heat exchanger, scrubber, recovery boiler…)
Obstacles: elbows, bifurcation, reduction, enlargement of the pipe section are brakes to the air move, represented by a pressure drop expressed in Pa, mmH2O, mbar, etc.
If
-∆p is the pressure drop in daPa
-v is the speed of the air in m/s, with v = Q/S (Q is the flow in m³/s and S the section of the pipe in m²)
-ρ is the density of the air in kg/m³,
We have:
∆p = K x v² x ρ / 20, K, is the factor of the pressure drop of the considered item (ex: elbow K=0.1 to 0.5 according the design)