To get this achievement, you must play on realistic difficulty in the 4th zone of the level "Under Construction". While it says you must play it on co-op, that is not the case, you can achieve this on solo. The strategy I used when playing was to eliminate all but one guard, then use my sonar goggles to find all of the canisters and fire extinguishers. Just make sure to put a mark on the guard, so you know where he is at all times. There are a total of 10 explosive canisters and 8 fire extinguishers.
On the 1st floor, there are 4 explosive canisters and 5 fire extinguishers.
On the 2nd floor, there are 4 explosive canisters and 2 fire extinguishers.
On the 3rd floor there are 2 explosive canisters.
Behind the weapons crate at the beginning of the level, there is 1 fire extinguisher.
The only one that is really easy to miss is the one at the beginning of the area, in the room that you just came from. If you watch the video provided, it is at the 7:38 mark. Also, it is in debate amongst some gamers whether or not you have to get detected with reinforcements being called or not. When I did my run, I had back up called just to be safe. The achievement will unlock once you kill the last guard, so if you are worried about the achievement not popping due to missing one, try completing the level.