Piston effect pressure difference

Upper limit for the piston effect for an elevator with enclosed lobbies

Reference

Hurley, M.J., et al., 2016. SFPE Handbook of Fire Protection Engineering. 5th ed. Springer.

Equations

\Delta P_{u,ir} = \dfrac{\rho}{2} \cdot \left(\dfrac{A_s \cdot A_e \cdot U}{A_a \cdot A_{ir} \cdot C_c}\right)^2

Air density in hoistway ( \rho ) — kg/m^{3}

Cross-sectional area of shaft ( A_s ) — m^{2}

Effective area ( A_e ) — m^{2}

Elevator car velocity ( U ) — m/s

Free area around elevator car ( A_a ) — m^{2}

Leakage area between building and lobby ( A_{ir} ) — m^{2}

Flow coefficient for flow around car ( C_c )