Question about Type VII ballast tanks

[Feldpost]

Originally Posted by Onkel Neal

...In the pictures of the valves 1, 2, 3; they are painted black on U-995, any idea why? Are these possibly fuel lines?

(Assumption) From the shape and location i don't think these are fuel lines. That close to the conning tower and 'shaped' like air valves these could be valves for fresh air into the different compartments of the sub(?).

Originally Posted by Onkel Neal

...
The red bar handle, any idea what this does? What kind of valve it operates? It seems like a quick-opening valve of some kind.

(Assumption) Quick 'Entlüftung der Tauchzelle #3' (flooding of cell #3); or more likely the 'Untertriebszelle' (for quick alarm diving)?
Where is it located? - Stern / port of command room? - On the far left of the picture the vertical-scale (could be a kind of fill/pressure-indicator for a cell), could be a hint too (but when stern/port than these could be an indicator for MBT#2)...