4-35 2000-OSM, F1
will reduce the classification to Nonhazardous/General Purpose. Since the Y and Z Purge systems
are identical except for nomenclature, the following explanation applies to both.
The purge air enters the analyzer system through a pressure regulator, an orifice, and a gauge used
to set purge flow, and then into the electronics housing where purge air flow is maintained until a fault
condition exists.
When a purge air alarm condition exists, the GCC will set an *** ALARM *** signal display on the
screen and cause a purge alarm contact to switch. A Y or Z Purge alarm alerts you to the condition,
but it does not turn off the analyzer.
NOTE
It is the customer’s responsibility to connect the purge alarm contact to a visual or
audible annunciator located in a constantly monitored area, as referenced in NFPA
496 (2003) and IEC 60079-2:2001.
Purge time depends on the application. Refer to the analyzer label or Data Package for specific
analyzer purge time.
X Purge Operation
While X Purge (see Figure 4-36 for features and Figure 1-1 for location) is an optional feature, some
installations specifying certification require it. X Purge reduces risk by two levels and turns off the
analyzer when an alarm occurs.
CUSTOMER
POWER
CONNECTIONS
L1 (HIGH)
L2 (NEUT)
GND
OVERRIDE PUSH BUTTON
1 2 3 4
TB70
Figure 4-36. X PURGE WITH COVER REMOVED
When you turn the power ON, X Purge begins monitoring the electronics housing (GCC and Purge
Air Panel) air purge pressure. When the air purge pressure reaches the specified level, the X Purge
starts a timed cycle. If the air purge pressure remains at the specified level during the timed cycle, X
Purge will supply power to the equipment when it completes the timed cycle. If the air purge pressure
drops before the X Purge completes the timed cycle, X Purge resets the timer and starts over. It
continues to reset the timer until the analyzer achieves and maintains the correct pressure for a
complete timed cycle. The X Purge will not supply power to the analyzer until it successfully
completes the timed cycle.
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