work their way down the rows 57 of separating media at the bottommost separating medium 56 at the front of the holder 42 it is believed that a vortex will be created which will enhance passage of the fats and oils into the trough 74 advantages arising from this are that the separating media 56 58 towards the rear of the holder 42 remain more or less dry thus ensuring effective secondary separation of residual fats and oils still present in the air after it has passed through the initial layers 82 of separating media additionally the wet u2018 filter face u2019 provided by the first few wet rows 57 of separating media 56 58 will assist in capturing carbon and other solid particles present in the air causing them to adhere to the front screen 60 and to the separating media 56 58 in the rows 57 and washed down with the condensed liquids fats and oils thus ensuring that the separating means 40 as a whole remains cleaner typically the linear velocity of the air through the separating means 40 is in the order of 3 2 m s however on the air exiting the outlet opening 52 in the holder 42 a drastic reduction in velocity is experienced due to the size of the air chamber 14 this it is believed will contribute to preventing fat and oil droplet carry over from the separating means 40 into the chamber 14 it is also believed that the combination of the separating means 40 trough 74 combination will facilitate maintenance for example the combination cannot be fitted incorrectly due to the clips that retain it in position secondly it is easy to remove clean and re install.