2054153-A is referenced by 3 patents.
A gas monitor which activates an alarm when a particular gas concentration is detected has means to inhibit alarm actuation when the detected concentration does not result solely from a concentration change. As described a low oxygen content (17%) alarm is prevented from actuation during sudden drops in ambient pressure. The inhibition operates with a sudden pressure drop curve B but not with a steady oxygen content drop curve A. Inhibition is produced when the rate of change of oxygen concentration exceeds a predetermined value e.g. the time for the oxygen content to decrease from 19% to 18% is less than a predetermined value.