Abstract: An anticipatory flammable gas detection system is provided for quickly determining whether the rise rate of gas concentration will approach a potentially hazardous level. The system includes a detector for determining the rise rate of the gas concentration and a comparator for determining whether the rise rate exceeds a potentially hazardous level. An integrator or multivibrator is provided for determining how long the rise rate exceeds a predetermined value. If the rise rate exceeds the predetermined hazardous rate of rise for more than a predetermined period of time, an alarm signal is generated. Prevention of false alarms is accomplished by providing another comparator which determines whether the magnitude of gas concentration exceeds a preselected percentage of the lower flammable limit. Should the magnitude be less than the preselected percentage, the alarm signal will not be generated.