Jarhead,
1. Pipe analyzers use power, but gas sensors don't.
2. You can do what you're talking about using gas sensors.
3. The script does already check for unsafe levels of volatiles and pollutants.
(If you wanted to use pipe analyzers instead of gas sensors for some other reason, that's a different matter, though it would require editing the script.)

Can you do an alteration to this so it not only works on pressure but also gases?

I think it could do this if instead of using gas sensors outside of this is instead just use 1 gas sensor inside and use pipe analyzers on the pipes going to each room outside this.

Because you have active vents inside but passive outside so pipes are showing what is in the room on each side.

So if both rooms are breathable (no pollutants, volatiles, and below x% co2) then bulkhead mode but if 1 room is unsafe (lung damage or death) (can also do temperature) then airlock mode. Then we (the end user) can just use this for all airlocks and be safe no matter what planet we are on (I think it adjusts the internal pressure to outside in direction your going already).

If I knew how to code the ic I would try to alter this myself.

says error at line 116. No idea how to repair.

in this case I have a second door

Great Idea.