need help in black plague

[highpoly]

-im in the building where i killed the woman that helped me ... i need to get 6 chemicals , i only found 5 in the room where the machinery to mix them is ... the entrance to the chemical lab is closed , i opened the door from the computer , but is still closed due to the gass leak ...
-i looked everywere , i cant find the sixth chemical ... neither can i stop the gass leakege ...

need help

ps : the game is awsome

when u enter the room look on the left sides thre wiil be pipe in s sahpe
replace it with the broken one

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when u enter the room there will be long pipes in the left side on the wall go near them you
will find a s shaped pipe on the floor replace it this after few seconds the door will open