Mess hall bug !

[TheBlastPassage]

Here's how to light the barrel on fire (spoiler):

Spoiler below!

The barrel is to be lit via the broken electrical box. What you do is drag the barrel in front of it, then pull down the lever. Doing so will cause the broken electrical box to release an array of sparks that will ignite the gasoline-soaked contents of the barrel. You are to then drag the barrel so that it is positioned under the sprinkler/smoke detector

If you already know how to get the barrel lit, and are saying that when lit, the barrel gives off no flame effect, here's what you do:

Open the game options and find 'Shader Quality' Lower that to 'Low' or 'Very Low' and see if that helps. Lowering the shader quality is an easy way to resolve some graphical errors/glitches.
Hope this helps