Andy Champ wrote:

You know those big cooling towers on power stations? The turbine
exhaust is into a partial vacuum...

Indeed so. Some low pressure turbine casings include a special
explosion vent comprising a thin metal sheet normally sucked onto
a mesh frame, with a sharp spike poised above it. If pressure
becomes positive, the metal bulges and is pierced by the spike to
vent to atmosphere. I remember working on the control relays
which, as vacuum fell, opened the turbine hall roof vents, so
that the anticipated blast didn't take all the windows out.

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.