Hmmm.
Does that mean they are immune to mesons?

No, unfortunately mesons ignore this armour as well.  It does work very well against all other weapons, especially early in the game when weapon damage tends to be low.  I can easily have the armour tech for the level 2 fuel bunker while firing 15-20cm weapons or missiles that are only doing 9 points of damage.  

Brian

Their armour level actually goes back to the old armour design where each point of armour negates one point of damage hitting the ship.  As such they armoured fuel bunker 1 stops the 1st point of damage.  If that is all the damage then the fuel tank is undamaged.  By the time you are at level 3 you are negating the first three points of damage done, wich can be significant as this means most light weapons will not penetrate and take out your fuel tanks.  

That being said they are primarily for main combatants and not small craft or carriers.  They are to large for the small craft and the carriers need lots of fuel to keep their fighters/fac's flying.  I do tend to put a couple on all of my warships above 100 hull spaces (5000 ton) even if the rest of their fuel is in regular fuel tanks so they are not as likey to lose all of their fuel in the middle of combat.

Brian

Just curious if anyone incorporates Armoured Fuel Bunkers in their designs at all?

They don't seem to hold that much fuel so I assume their intended for FAC's rather then ships?