AFT Application Topics
Engineers involved in the design of buildings know that any proposed design must comply with the exhaustive list of codes and standards that have been implemented to ensure safe occupancy of the building. These standards include strict requirements for many aspects of the structure such as building heights, interior finishes, roof construction, etc. Of particular interest to those engineers involved in the design of the fire protection system is to ensure that their design allows for sufficient flows and pressures at each nozzle.
In the interest of designing the fire water system conservatively, engineers use NFPA codes 13 and 15, which often include hand-calculation methods that allow for satisfactory approximations.
AFT Fathom can quickly simplify the calculations around the design of fire water protection systems by automatically determining the hydraulically most remote spray nozzle (using the GSC add-on module), as well as the resulting flows and pressures at each nozzle. Because the fundamental equations of incompressible flow are solved simultaneously, there is no need for AFT Fathom to incorporate the approximations described in the NFPA codes. AFT Fathom instead reports the values that allow the governing equations of fluid flow to agree. Users can model fittings and losses with the Equivalent Lengths method, and the Hazen-Williams friction factor can be used to model pipe pressure loss due to friction. AFT Fathom also conveniently automatically provides the results of the hydraulic calculations in the format outlined in the NFPA report (see Figure 1).