The filter system comprises one or more pressure vessels known as filter towers with either prepacked cartridge or loose filter media, a back pressure valve, one or more pressure gauges, and a coalescing separator. After passing through the final intercooler coil the compressed air passes through separators to mechanically remove condensed water and oil droplets, after which other contaminants re removed in the filters by chemical bonding, absorption and catalysis. The first filter medium is desiccant, as water contamination can reduce the effectiveness of some of the other media. Next is the carbon monoxide converting catalyst (if used), then activated carbon, and finally a particulate filter, which will also catch dust from the filter media. The ratio of desiccant to activated carbon will be somewhere around 70/30.