Abstract: Explosive gas concentrations in a subterranean atmosphere can be monitored, not by measuring the concentration of the explosive gas directly but, according to the invention, by monitoring a second parameter of the atmosphere, e.g. oxygen concentration, and calculating the level of the combustible gas from this measured value.

Abstract: Mine ventilating atmosphere parameters, e.g. methane concentration, can be measured according to the invention with an arrangement which has a continuously operating first measuring system to which a second measuring system is periodically connected to measure the same parameter with its output being utilized to control the zero point or sensitivity setting of the first measuring system.

Abstract: A measuring and evaluating device and method for mine galleries and the like can monitor the various parameters of the atmosphere and normalize the parameters for display and storage in the device. In an emergency the danger-posing operations of the device are shut down although the memory is maintained and, for further safety, a detector which may pose a danger may be inactivated and replaced by a less precise detector for the same parameter but which poses no danger.

Abstract: A multiplicity of environmental parameters, such as composition of the ambient atmosphere, temperature and air pressure, are concurrently measured with a portable device and registered together with information giving time and location of each measurement. The readings are interrelated parameters, e.g. temperature and relative humidity, may be jointly evaluated with adjustment of the stored values in light of one another; they may also be subjected to other corrections such as linearization, averaging or logarithmic conversion. A keyboard on the device enables the instantaneous readout of a selected parameter on a common display panel; detection of dangerous concentrations of noxious gases, e.g. firedamp in a coal mine, sets off an alarm.