downstand vent.

[феруза]

Пожалуйста, помогите перевести spill edge, downstand

Выражение встречается в следующем контексте:

Where the smoke flow directly approaches a spill edge with no downstand, e.g. where the ceiling is flush with the top of the opening, Cd = 1,0. For other scenarios the following procedure can be adopted.

Dw is the flowing layer depth in the plane of the opening, measured below the bottom of the downstand in metres (m) or below the soffit if there is not downstand at the opening

Заранее спасибо