Hygrade’s packed tower scrubbers are built to the counter-flow principle, cleaning soluble and noxious gases with a scrubbing liquor as they pass through inert media. The gas or air stream travels up the tower, meeting downward flowing scrubber liquid. Gas absorption comes either through physical contact and the dissolution of gas in water or by the chemical reaction between the gas and the scrubbing reagent. Key to efficiency are the packing surface area of the gas or liquid transfer, even distribution of the scrubbing liquor throughout the packing, and the gas velocity and liquor flow rate throughout the packed bed. Gases removed by these types of scrubber include hydrogen chloride, ammonia, nitrogen oxides, sulphur dioxide, phosgene, chlorine, hydrogen sulphide, amines, bromine, nitric acid, methanol, and formaldehyde.