Abstract: A gas quantity setting system, such as for the testing and/or certification of "low emission vehicles", provides a dilution air/exhaust gas mixture for investigation and has a continuously cross-sectionally variable, venturi nozzle and an axially adjustable conical, nozzle needle. The nozzle needle of the venturi nozzle is adjustable by a computing device, taking into consideration a temperature, a pressure and measured values of a mass rate of flow meter, in such a way that a dilution ratio (dilution factor) of the exhaust gas has a predetermined, preferably constant, value in spite of fluctuations in the feeding of quantities of exhaust gas.

Abstract: An exhaust-gas analyzer, particularly for emissions testing of motor-vehicle engines has a sampling tube into which a mixture of exhaust gas and ambient air is fed through gas lines. A gas feed pump is disposed downstream of the sampling tube with a flowmeter inserted in the air line feeding electrical signals to a computing unit. The unit computes instantaneous standard total flow rate, allowing for gas pressure and temperature.

Abstract: An exhaust-gas analyzer, particularly for emissions testing of motor-vehicle engines has a sampling tube into which a mixture of exhaust gas and ambient air is fed through gas lines. A gas feed pump is disposed downstream of the sampling tube with a flowmeter inserted in the air line feeding electrical signals to a computing unit. The unit computes instantaneous standard total flow rate, allowing for gas pressure and temperature.