Old Dallas Civil Defense Emergency Operations Center , On The Surface
Here's a short video showing the air intake and exhaust blast valve ventilators on the surface. These blast valve ventilators came from the Nevada nuclear test site. I have copies of the letters sent by the City Of Dallas when these valves were procured on my civildefensemuseum site in the virtual shelter tours, old Dallas EOC section. I found the letters in the City Of Dallas Archives. I even found the shipping receipt. If would have been really cool to find documentation that the ventilators were tested in an actual nuclear test!