109:41:53 Armstrong: (Laughs) A particularly good thought.
[The hatch can be opened from the outside, if necessary. The reason for almost closing the hatch is, I believe, to prevent radiative cooling of the cabin. Neither Neil or Buzz remembered any specific reason.]
[Armstrong (straight-faced) - "To avoid having somebody say 'Were you born in a barn?'"]
[Aldrin - "Now that you bring it up, what would have happened if the valve had gotten screwed up or something and it started re-pressurizing?"]
[Armstrong - "You'd never get back in."]
[Aldrin - "Did we really ever investigate that problem? (Chuckling) It probably would have been a good idea to use a brick or a camera to keep it from closing. Somebody must have thought about that."]
[I recalled that the dump valve could be opened from the outside.]
[Aldrin - "We had a handle (on the outside) to unlatch it. But, considering the difficulty we had, if you had a couple of psi (in the cabin), you'd never get it open. (Half seriously) Well, you'd get it open, but you'd never get the bent hatch closed again."]
[Actually, the handle is the weak point.]
The dump valve link then says:
Setting the internal handle to the dump position unseated the poppet. With a bacterial filter installed, the forward hatch valve could dump pressure from 5.0 to 0.08 psia in 310 seconds without cabin oxygen inflow; without a filter in place, either valve could dump cabin pressure to 0.08 psia in 180 seconds; and, with both open and no filter in use, the time was 90 seconds. Setting the handle to the closed position prevented the valve from opening at normal pressures, if the servo valve failed.
Question: Why would there be a bacterial filter in a valve used to dump the atmosphere of the lunar module before opening the hatch? Who or what was being protected from what bacteria from what source?