TM 10-6640-239-13 2-9 e. Purge System and Gas Alarm Controls and Indicators.  Figure 2-6 and Table 2-6 list the controls and indicators of the purge system and gas alarm system. Table 2-6.  Purge System and Gas Alarm Controls and Indicators Index Number Control or Indicator Function 1 Detector Selector Switch In AUTO mode meter responds to channel with strongest signal. Turned to channel 1 or channel 2 position meter responds to signal from selected channel. 2 Indicator Meter Indicates concentration of combustible gas at detection point. 3 Gas Alarm Pilot Light, Green Indicates gas alarm power is on and detector circuit is energized. 4 Alarm Indicators Illuminates to indicate which remote detector an alarm condition is present at.  Light goes out when alarm reset switch is pressed and no alarm conditions remains. 5 Warning Indicators Illuminates to indicate which remote detector a warning condition is present at.  Light goes out when alarm reset switch is pressed and no warning conditions remains. 6 Fail Indicators Illuminates to indicate which remote detector a fail condition is present at.  Light goes out when alarm reset switch is pressed and no fail conditions remains. 7 Alarm Reset Switch When pressed, deactivates holding circuits of alarm and warning relays if a safe gas condition has been restored at remote detector.  If a safe condition does not exist, unit cannot be reset. 8 Warn/Test Light, Yellow Indicates combustible gas condition exceeding low alarm setting exists at remote detector, or when alarm test switch has been activated.  When pressed, provides a simulation of an alarm level of gas concentration at remote detector.  Also provides a functional check of the analyzer and remote alarm circuit. 9 Gas Alarm Fail Light, Blue Indicates gas alarm failure or malfunction. 10 Gas Alarm Light, Red Indicates combustible gas warning 11 Purge Doors Limit Switches Provides signal to purge alarm buzzer if one of purge doors is not opened when purge cycle is initiated.