Compared to DIN EN 737-3 the monograph “Aer medicalis” in the appendix to the European Pharmacopoeia includes essentially altered purity features whereas especially the drastically reduction of the dew point temperature to -46°C atmospheric (this corresponds to 67 ppm V/V) leads to considerable difficulties. The value 67 ppm V/V for water equals the point of condensation at a pressure of 200 bars and a temperature of 11 ºC. This limitation of the water content to the point of condensation is necessary since the condensation of water may cause corrosion damages and furthermore can favor the increase of microbes.