BS 9999 | Ch. 15 | Fig. 6b

Merging flow from stair above and from stair below final exit level

Calcualtes the merging flow from stairs above and below the final exit level

Reference

British Standards Institution, 2017. BS 9999: Fire safety in the design, management and use of buildings - Code of practice. BSI.

Equations

W_{FE} = S_{up} + S_{dn} or W_{FE} = B \cdot X + 0.75 \cdot S_{up}

Stair width for upward portion of the stair ( S_{up} ) — mm

Stair width for downward portion of the stair ( S_{dn} ) — mm

Number of people served by the stair from below the final exit level ( B )

Distance from the nose of the top going of the downward portion of the stair ( D ) — m

Minimum door width per person ( X ) — mm/person