Combustible gas concentration monitor for mining and industry - uses catalytic cell and electronic economy circuit operating alarm with multivibrator controlled by concentration signal

摘要

The gas concentration monitor for mines and industrial plant consists of a pre-heated catalytic gas detector cell whose output signal drives an indicator (4). The detector signal is also taken to a level detector circuit (7) so that at a certain gas concentration, this produces an output signal. This signal controls a multivibrator (2). The multivibrator periodically switches the gas cell away from the separate DC battery supply (1) and activates an alarm unit (8). If the battery voltage should fall below a pre-set level, the alarm unit is held in the energised condition if a critical gas concentration is present. This operation is carried out by an electronic relay (6).