[Polizeiposaune]

There are normally-open air-tight hatches between modules. Various utility connections and air ducts are normally run through the open hatches so it would take a bit of work to disconnect these connections before they could be closed.

Not exactly something you want to be doing under time pressure.

[basch]

What’s the reason against separate conduit for utilities?

[Zigurd]

If such a conduit would connect two sections that the hatch is meant to isolate, you would have to make the conduit and everything running through it airtight, even under a catastrophic loss of air. If the conduit didn't seal as well as the hatch, which is meant to withstand hard vacuum on the other side of it, it would defeat the purpose of the hatch.

[7952]

Most stuff runs outside of the capsule including power and dangerous ammonia. They use connectors that fit to the hull and have plugs on each side. Gases/liquids can be controlled with valves. And parts can fit tightly together to make a seal. The stuff running through the hatches is designed to be quickly disconnected in an emergency.

I guess the main question about this kind of routing is if things are safer kept on the unpressurized side or not. And that the risk of a small hole on the hull is offset by reducing the risk of leaks in the pressurised area.

[numpad0]

They just didn't have enough of reserved general purpose connections for future use. I guess this woild be especially the case with the Russian modules, which were literally surplus Soviet manned space army outposts(such a thing do not make a lot of sense, they did it anyway).

[PaulHoule]

This one

https://en.wikipedia.org/wiki/Salyut_3

had a machine gun!

[Mistletoe]

What was the gun for?

[krapp]

Shooting American spacecraft. What else would it be for?

[necovek]

If it made pew-pew sounds (inside the station, obv), mission accomplished regardless of it actually being able to shoot anything down, up or everywhere.

[nkrisc]

Those would need to be connected during docking and sealed separately anyway if you wanted to seal the hatch. More failure points.

[NegativeLatency]

Just a guess: Harder to build and operate with more failure modes and less opportunity for intervention.

[gpm]

You'd still need to pull out the utilities and close a now second hatch in the conduit to seal the thing. What would be the point?