Gas concn. measuring and monitoring device - has two independent measurement bridges, one based on heat conduction and other on heating effect principle

摘要

The gas concn. measuring device has two independently adjustable measurement systems, one based on the heat conduction principle and the other on heating effect principle, with measurement elements exposed to the gas mounted in a common chamber. An indicating instrument is provided for both systems. When the device is switched on, the measurement bridge based on the heat conduction principle is switched on through a monostable flip-flop, a first threshold switch and a first switching transistor. When gas concn. is low, the system with measurement bridge based on the heating effect principle is switched on later through a second switching transistor. When gas concn. rises the monostable flip-flop trips again through a second threshold switch and an RC circuit. L.e.d.s signal connection state of the two systems.