Abstract: An apparatus for continuously measuring the hydrocarbon concentration in a gas flow includes at least one flame ionization detector with a combustion chamber housing electrodes between which a current flows due to ionization in the area of a burner flame. The combustion chamber of the flame ionization detector is connected to a suction pump in form of a venturi tube for applying an underpressure in the combustion chamber so as to allow especially sample gas but also burner gas and oxidizer to be drawn into the combustion chamber.

Abstract: A method and an apparatus for the continuous monitoring of a gas mixture which contains explosive gases, for example in drying furnaces of painting or coating plants, with the concentration of the gas mixture being at an adequate distance from the so-called lower explosion limit includes the monitoring by means of flame ionization detectors. On occurrence of a fault an alarm display is actuated and firstly the respective flame ionization detector itself is checked and if necessary recalibrated. If the alarm persists after this recalibration, suitable steps must be taken in the plant itself, for example fresh air can be blown into the plant or the latter can be shut off.