black plague.. machine room bug

[noodles385]

Hi to all.:

I'm playing Penumbra Black Plague and having problems when entering the machine room. As a matter of fact I noticed that when I enter the machine room, after passing the automatical doors, I have no more need of the gas mask even if the valve (the one on the right with the red light above) is still open. I read some walkthroughs and you can put off the mask only after closing the valve with the computer terminal.
Is this a bug? I have the game unpatched. So can I solve this problem with the patch? If not, is there another solution? Thanks a lot in advance for your help. Bye.

PS: I've read the list of fixes of the patch 1.01 and found this:

-Added alternate solutions to puzzle in level 2 & Level 4.
-Corrected portal setting in Level 01.
-No longer possible to be pushed outside of level when coming to level 03 from level 01.
-Added "collide character" to electric locker in Level 01.
-The alarm sound is not triggered if player has already locked himself in the room, level 19.
-Door04 is now locked in Level 7 during the intro sequence.
-Fixed minor glitch during an event in Level 7.
-The hand is not able to fall down the hole in Level 10.

what do level 1,2,3,4,.. mean? how I can see what level I'm playing?