Emancipation Grid
An Emancipation Grid (also Emancipation Grill or more commonly, Fizzler), is a special energy field in Portal 2 which resets the portal gun of any player (destroying both portals) and vaporizes other objects that touch it.
In Portal, the Emancipation Grid is composed of two models, a trigger-textured invisible trigger_portal_cleanser and a particle system emitter (info_particle_system).
In Portal 2, however, it is composed of an entity (trigger_portal_cleanser) combined with a pair of models (fizzler.mdl). The brush used for the trigger should be nodraw except for the two visible faces which have a fizzler texture on them.
Instance
As with most of Portal 2's testing elements there's an instance for this gameplay element as well. These are static and are only 128x128 units, they were specifically designed to work in conjunction with the turbine elevator, so it's use is very limited. However it comes in three designer colors, including decayed black and white, and clean black.
- instances/gameplay/fizzler_black_clean_128x128.vmf
- instances/gameplay/fizzler_black_dirty_128x128.vmf
- instances/gameplay/fizzler_white_dirty_128x128.vmf
Manual Creation
This tutorial aims to be easy to understand even to user with little or no knowledge of hammer.
Step 1
Create a prop_dynamic and, for this tutorial, "models/props/fizzler.mdl". There are a few more "fizzler" models for use in the Old Aperture themed maps, and for dynamic 'open-close' sequences.
- models/props/fizzler.mdl
- models/props/fizzler_dynamic.mdl
- models/props_underground/underground_fizzler.mdl
- models/props_underground/underground_fizzler_wall.mdl
These are the main four, although there are more models, some more detailed and some less.
Step 2
Now you would like to place one model at each end of the area you would like things would get 'fizzled' in a way they both face each other. The fizzler model, as you might have noticed, sinks in the wall to let the closing animation to be played if necessary; even though we are using the 'static' model the socket is still there.

To solve this we would make three brushes that surround the fizzler from the back, sides and part of the front (note that the side brushes would be the front side too), don't forget to tie these brushes to a func_detail.
We would now make two brushes, each 32x8 units and 128 units tall, we would place them on each side of the fizzler's model. Make sure the fizzler's attachment panels sit each on a brush as seen in the picture. Add one more brush behind the model to seal off the void (if there's another wall there already, there's no need for it). Texture these brushes with the appropriate wall texture, even the inner parts; texture only the part that won't be seen in "nodraw".
Step 3
Create a brush using the 'nodraw' texture, extending from one fizzler model to the other. This will act as the emancipation area. It should be one unit thick and 128 units high. Tie the brush (pressing Ctrl+T) to a "trigger_portal_clenser" entity. Hit apply and set "Visibile?" to yes.

Make sure you checkmark, in the flags tab, the "Physics Objects" if you want things other than your portals to be removed when touching it, like cubes and turrets.
Step 4
Open the Texture Application tool and select only the front and back faces of the fizzler, the parts that will be seen. Click "Browse" and filter "fizzler" select "effects/fizzler" and change the texture scale to 0.13 on both the X and the Y axis, now click "Apply".
You should now have a working fizzler! If you name the it you can open and close it through the I/O system, in this cade don't forget to chose a "models/props/fizzler_dynamic.mdl" and to add proper animations when it's closed and opened.
Larger Fizzlers
Sometimes a fizzler should be higher or wider than 128 units, but as the fizzler model is only 128 units tall a set of another two fizzler models, and brushes, on top the ones you just created are required. To do this, simply copy-drag everything you just created 128 units up, repeat as many times as necessary.
Do not stretch the brushes to the height you need, as you want only a part of the field to flash in white when a portal hits it; For consistency official maps use this approach.
To make the fizzler wider we would need to split the brush to three parts. Just use the clipping tool (Ctrl+X) on the sides closest to the models, make sure both sides of the clip remain (both are highlighted in white). These two new brushes should be 128 long. The middle brush, should stretch between these two brushes - it doesn't matter his length. Again, open the Texture Application tool and color both front and back sides of the middle brush with "effects/fizzler_center", one of the other brushes with "effects/fizzler_l" and the one left with "effects/fizzler_r".

Theory
These should be used wherever you don't want the player shooting one portal in one area and another in a second, and when you don't want the player to bring objects into another area. These destroy portals and objects.
External links
- Example map using this tutorial. VMF included.