fan static pressure in round duct
 

Hello
In dust collection systems we have the well known ACGIH (American Conference of Governmental Industrial Hygienist) method for the calculation of the static or total pressure of the fan, i like know how use of solidworks floworks simulation to compare the results on both methods.
Right now i can calculate the static pressure required to get a transport speed of 3750 ft/min on a straight duct of 6 in of diameter and 2 meters of length, (ACGIH method). this gives me -1.9554 inWg.
On the other hand i'm making a floworks study, the same duct, i have as the boundary conditions: 1)in one end of the pipe an outlet velocity of 3750 ft/min and 2)on the other end of the pipe a pressure opening at environment pressure of 14.695 lb/in2, The goals i'm defining are static, total and dynamic pressuresplus the velocity in both ends of the pipe.
The problem is that the results of the pressures not match the results i'm getting with ACGIH method and the velocities doesn't match the 3750 ft/min i declare in the boundary conditions.
I hope you guys can help me with this, thanks in advance

Hello Brytney, i do not think the problem is in the ACGIH method, in the attached file mathcad-6in round duct.mcd you can see this calculation.
i also have attached the results of the simulation in solidworks flow simulation (goals1 file), the upper table are the results given by slw flow simulation, the lower table are conversions to relative pressure and to inWg.
As you can see the static pressure value is far from the value of the calculation, the velocity pressure is almos equal in simulation and in calculation, the flows in both lids are diferent from the value i specify in the boundary condition outlet velocity1.