Put a portal on a white wall above the iron bars, and put a portal of the other color near you. Go through. Do this again to go up to the iron bars above you.
Now look around at the walls to find a door in the wall where there is a ledge. Above the door, there is an angled wall. Put a portal on the angled wall, then put a portal on the floor below you. Fall into the floor portal and you will end up on the metal platform up above.
There is some blue gel dripping on the floor here. Leave the portal on the angled wall, and put a portal of the other color under the blue gel. This will coat a piece of angled wall with some blue gel.
Leave the portal on the angled wall that the gel is coming out of. Now look at the floor and put a portal there of the other color. Fall through it. You should bounce off of the angled wall that you just coated with blue gel. You'll be tossed to a higher level. There is a white floor up here. Put a portal there. Now drop down one level.
From here, make sure you know which color of portal you put on the level above you. Make a portal of the other color on the floor down below. fall into it. As you go up, look for the white floor on the level above. Put a portal there. Use a portal of the other color to access the upper area.
Now just walk toward the emancipation grill and go through.
There are some bright lights on the wall facing you. Go toward there. The ceiling there is white. Put a portal there. Now put a portal of the other color under the white gel. This will coat an angled wall and a flat part of the wall with conversion gel.
Put a portal at the bottom of the wall that just got coated with conversion gel. Now put a portal of the other color under the orange gel. This will create a streak of orange gel on the floor.
Finally, put a portal on the angled part of the conversion gel wall, then put a portal of the other color directly below the first portal. Go to the far end of the room and run along the orange gel. You'll bounce off of the blue gel and go through the portal on the upper part of the wall, coming out through the angled part of the wall. You will land on the level above.
Put a portal on the white piece of floor. Now look down through the metal floor and put a portal of the other color under the white gel drip. This will put conversion gel on the ceiling.
Put a portal on the ceiling gel, then put a portal of the other color under the dripping blue gel down below. This will put blue gel on the spot on the floor where you landed after running on the orange gel and bouncing through the portals earlier.
Now go back down to the lower level. Make sure that the streak of orange gel on the floor is still intact. Use portals to put a fresh coating of orange gel on the floor if you need to. Then make portals on the angled wall and another directly below it and run along the orange gel like before. You should be bounced over to the platform in the distance.
Go around behind the column in front of you to find some dripping conversion gel. Look up. There is a white wall up there. Put a portal on that, then a portal on the conversion gel on the floor. Go through.
Walk to the end of the walkway and look up and left. There is an arrow pointing at a metal mesh with the number 09 under it. Make a portal on the angled wall at the base of the mesh. If there is no conversion gel coming out of this portal, go back and put a portal of the other color under the dripping conversion gel.
The conversion gel will be sprayed around the walls of the shaft above you because of the vents blowing the air around. The gel should reach all the way up to the ceiling high above you. Put a portal on that ceiling, then go back to where the conversion gel is coming from. Make a portal of the other color there and go through.
With luck, you will end up near the sign that says "watch your step". You can walk up the wall with this sign, even though it's steep. Walk up until you reach the arrow and the sign that says "gel pump station", where you can't go any farther. There are white walls past the mesh above you. Make a portal there and be sure to remember which color it is.
Walk part of the way down, then jump toward the railing next to the "watch your step" sign. You should fall down the shaft and onto the walkway that you were on earlier. Go into the room and make a portal of the color that you did NOT put above the metal mesh. Go through. You are now in the gel pump station.