Table 2-7. Purge System and Gas Alarm
Control or Indicator
1. Purge Doors Limit Switches
Provides signal to purge alarm buzzer if one of
purge doors is not opened when purge cycle is
2. Gas Alarm Green Pilot Light
Provides indication when the instrument power is
and detector circuit is energized.
3. Indicator Meter
Provides indication of the concentration of combustible
gas at detection point.
4. Gas Alarm Blue Fail Light
Provides indication when there is equipment failure or
5. Yellow Warning/Test Light
Provides indication when a combustible gas condition
exceeding the low alarm setting exists at the remote
detector, or when the alarm test switch has been
activated. When depressed, provides a simulation of
an alarm level of gas concentration at the remote
detector. It also provides a functional check of the
analyzer and remote alarm circuit.
6. Red Alarm Light
Provides test of alarm buzzer.
7. Alarm Reset Switch
When depressed, deactivates the holding circuits of the
alarm and warning relays if a safe gas condition has
been restored at the remote detector. If a safe
condition does not exist, the unit cannot be reset.
8. Detector/Selector Switch
Provides automatic or manual selection of individual