BS 9999 | Ch. 15 | Fig. 6a

Merging flow from stair with storey exit at final exit level

Calculates the merging flow for stairs where the stair and storey exit share a common final exit

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} + W_{SE} or W_{FE} = N \cdot X + 0.75 \cdot S_{up}

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

Width of the final exit level storey exit ( W_{SE} ) — mm

Number of people served by the final exit level storey exit ( N )

Lesser distance from final exit level storey exit or lowest riser from stair ( D ) — m

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