Abstract: The invention relates to a measuring instrument and method for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air. In order to develop a measuring instrument for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air, said instrument being suitable for detecting concentrations in the lower ?g/m3 range or in the ppb range and allowing measuring accuracy of 10 micrograms oil/m3 air at a measurement error in the single-digit percentage range, it is proposed according to the invention that the measuring instrument comprises an air or compressed-air connection and, connected thereto, a flow limiter to which a catalyst is connected that is connected in turn with a photoionization detector, switchable means being provided for routing the air or compressed air over the oxidation catalyst or past it directly to the photoionization detector.

Abstract: The invention relates to a measuring device for detecting the hydrocarbon fraction in gases. The measuring device is characterized in that the measuring device determines the hydrocarbon fraction in a first gas flow and a second gas flow, both the first gas flow and the second gas flow originating from the same gas source, the first gas flow being fed to the measuring device unchanged and the second gas flow being fed to the measuring device prepared.

Abstract: The invention relates to a measuring instrument and method for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air. In order to develop a measuring instrument for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air, said instrument being suitable for detecting concentrations in the lower ?g/m3 range or in the ppb range and allowing measuring accuracy of 10 micrograms oil/m3 air at a measurement error in the single-digit percentage range, it is proposed according to the invention that the measuring instrument comprises an air or compressed-air connection and, connected thereto, a flow limiter to which a catalyst is connected that is connected in turn with a photoionization detector, switchable means being provided for routing the air or compressed air over the oxidation catalyst or past it directly to the photoionization detector.