Thanks Dave but i still think you maybe missing the point, i am not saying that this is how the trap should work, only what would happen in an extreme circumstance. The ONLY reason i see for an air trap is to highlight a developing problem such as a suction air leak. This would show up as a bubble in the trap that is now alot easier to see. In extreme circumstances of air in the trap then it is highly unlikely to cause a flameout if a diffusser is fitted. Even better if this diffusser is custom built to limit pressure drop.