Stair Pressurization Estimator Disclaimer: This calculator is for estimating purposes only and is not for final design calculations. This does not take the place of a rational analysis and does not incorporate all factors that could impact stair pressurization. Consult a licensed fire protection engineer. Description Value Unit Building Inputs Number of Stories Stories Average Floor Height Feet Average Building Perimeter per Floor Feet Number of Stairways Stairs Stair Length Feet Stair Width Feet Total Length of Stair Wall Bordering Inside Feet Total Length of Stair Wall Bordering Outside Feet Stair Door Width 3 Feet Stair Door Height 7 Feet Number of Doors Between Stair and Building Doors Number of Doors Between Stair and Outside Doors Model Inputs Max Pressure Difference 0.35 in. H20 Min Pressure Difference in. H20 Construction - Outdoor Design Temp - Summer F Outdoor Design Temp - Winter F Summary Required Flow Rate - Summer CFM Required Flow Rate - Winter CFM Assumptions: All equations, calculations from Handbook of Smoke Control Engineering, 2nd Edition, Klote All stairs are uniform in dimension All stair doors closed Building/stair temperature is 70F Atmospheric pressure is 14.7 psi Parameter Abbreviation Value Unit Area Between Stair and Building ASB SF Area Between Building and Outside ABO SF Area Between Stair and Outside ASOu SF Area Between Stair and Roof ASOr SF Winter Outdoor Air Density ρo lb./ft3 Temperature Factor FT in. H2O/ft Flow Area Factor FR - Pressure Difference between Stair and Building, top PSBt in. H2O Pressure Difference between Stair and Building, botto PSBb in. H2O Pressure Difference between Stair and Building, avera PSBav in. H2O Pressure Difference between Stair and Outside, botto PSOb in. H2O Pressure Difference between Stair and Outside, top PSOt in. H2O Pressure Difference between Stair and Outside, averag PSOav in. H2O Mass Flow Rate between Stair and Building mSB lb/s Mass Flow Rate between Stair and Outside, wall leaks mSOu lb/s Mass Flow Rate between Stair and Outside, door mSOd lb/s Mass Flow Rate between Stair and Outside, roof mSOr lb/s Total Mass Flow Rate m lb/s Total Volumetric Flow Rate V CFM Summer Outdoor Air Density ρo lb./ft3 Temperature Factor FT in. H2O/ft Flow Area Factor FR - Pressure Difference between Stair and Building, top PSBt in. H2O Pressure Difference between Stair and Building, botto PSBb in. H2O Pressure Difference between Stair and Building, avera PSBav in. H2O Pressure Difference between Stair and Outside, botto PSOb in. H2O Pressure Difference between Stair and Outside, top PSOt in. H2O Pressure Difference between Stair and Outside, averag PSOav in. H2O Mass Flow Rate between Stair and Building mSB lb/s Mass Flow Rate between Stair and Outside, wall leaks mSOu lb/s Mass Flow Rate between Stair and Outside, door mSOd lb/s Mass Flow Rate between Stair and Outside, roof mSOr lb/s Total Mass Flow Rate m lb/s Total Volumetric Flow Rate V CFM