Abstract: A method for detecting the number of particles in the exhaust gas of combustion engines, wherein a value that is characteristic for the quantity of the particles is determined, for example, in form of the blackening of a filter or determination of the concentration, wherein, furthermore, the suction time and/or the suction volume of the exhaust gas are measured, and wherein, if necessary, the blackening rate is calculated, based on the characteristic value and the suction time and/or the suction volume by way of a first conversion function, wherein the number of particles is determined based on the characteristic value, the suction time and/or the suction volume as well as the data of the first conversion function by way of a second conversion function.

Abstract: In the course of a method for automatically operating a measuring device for measuring particles in gases, in particular for measuring carbon black particles in the exhaust gas of internal combustion engines, particle-related variables are repeatedly determined from the blackening of a filter paper in temporally limited individual measurements and the differential pressure caused by the flow of measurement gas is monitored via the internal measuring diaphragm, wherein the individual measurement is automatically terminated and an error message is output below a primary threshold value for the differential pressure.

Abstract: The invention relates to a measuring device (1), preferably a test stand for engines and vehicles for analyzing exhaust gases of a combustion engine (2), comprising at least one exhaust gas supply line (3, 4), which can be connected to the exhaust system of the combustion engine (2) and which supplies at least one measuring branch (7, 8, 9) each provided with a respective analysis unit (12, 13, 14) for determining exhaust gas constituents. According to the invention, a filter device (16a to 16f) is provided in at least one cool measuring branch (9) upstream from the analysis unit (14) and/or between different components (14a, 14b) of the analysis unit (14) and/or on the output side of at least one analysis unit (12, 13, 14) of one of the measuring branches (7, 8, 9). This filter unit contains a filter material that is selective with regard to gaseous hydrocarbons, preferably a filter material selected from the group consisting of zeolites and/or silicates.

Abstract: The invention relates to a measuring device (1), preferably a test stand for engines and vehicles for analyzing exhaust gases of a combustion engine (2), comprising at least one exhaust gas supply line (3, 4), which can be connected to the exhaust system of the combustion engine (2) and which supplies at least one measuring branch (7, 8, 9) each provided with a respective analysis unit (12, 13, 14) for determining exhaust gas constituents. According to the invention, a filter device (16a to 16f) is provided in at least one cool measuring branch (9) upstream from the analysis unit (14) and/or between different components (14a, 14b) of the analysis unit (14) and/or on the output side of at least one analysis unit (12, 13, 14) of one of the measuring branches (7, 8, 9). This filter unit contains a filter material that is selective with regard to gaseous hydrocarbons, preferably a filter material selected from the group consisting of zeolites and/or silicates.

Abstract: A method for determining the characteristic properties of soot particles originating from combustion processes utilizes the determination of the blackening of a filter paper. In order to allow for achieving a quick and relatively accurate determination of the particle sizes, possibly of further characteristics as well, a method of this kind provides that the pressure conditions on the filter paper are established as well. It is advantageous for this purpose to determine the differential pressure on the filter and/or filter paper caused by the deposition of the particles.

Abstract: A method for determining the characteristic properties of soot particles originating from combustion processes utilizes the determination of the blackening of a filter paper. In order to allow for achieving a quick and relatively accurate determination of the particle sizes, possibly of further characteristics as well, a method of this kind provides that the pressure conditions on the filter paper are established as well. It is advantageous for this purpose to determine the differential pressure on the filter and/or filter paper caused by the deposition of the particles.

Abstract: A process is provided for measuring the opacity in gases, especially in exhaust gases or in the atmosphere, at or near the maximum of the eye sensitivity in the green wavelength range with a central wavelength lying between 550 and 570 nm. In order, in a simple manner, to separately determine the components which are responsible for clouding in the visible wavelength range, or to make a correction possible by taking into consideration further components that have an effect in the visible range, the opacity in at least one second wavelength range which is located in the spectral between 200 nm and 2&mgr;, and which overlaps at most slightly with the first wavelength range is additionally measured.