Purge time depends on the application. Refer to the analyzer label or Data Package for specific
analyzer purge time.
5.6.2 X Purge operation
While X Purge 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.
When you turn the power ON, X Purge begins monitoring the electronics housing (PGC 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.
The X Purge cycle time depends on the application, and it may vary with analyzer configuration and
condition. Refer to the analyzer label or Data Package for specific purge specifications. Once X Purge
applies power to the analyzer, power continues to the analyzer as long as the electronics housing
maintains air purge pressure.
X Purge removes power from the analyzer when the electronics housing air purge pressure drops
below specifications. It locks out power to the analyzer and causes a purge alarm contact to switch.
The analyzer has connections available to the customer for connecting the purge alarm to a visual or
audible annunciator located in a constantly monitored area.
In order to re-start the analyzer after an X Purge alarm, you must first correct the cause of the drop
in pressure. Then turn the power OFF at the circuit breaker for at least ten seconds and turn the
power back ON. This starts a new X Purge timed cycle which it must complete before it will supply
power to the analyzer. If you do not correct the cause and cannot achieve and maintain pressure, the
X Purge will not complete the cycle and will not supply power to the analyzer.
5.6.3 X Purge override
When X Purge removes and locks out power to the analyzer after a drop in electronics housing purge
air pressure (or before pressure has initially attained the specified level), you can use override to
provide power to the analyzer for troubleshooting or maintenance purposes. Override does not cancel
the X Purge power lockout but temporarily overrides it.
Should the analyzer’s automatic safety devices of the Purge Control Unit be defeated or bypassed
during operation, such as for maintenance purposes, the user of the analyzer shall adhere to the
requirements of standard IEC 60079-17:2013, for Electrical Installations, Inspection and Maintenance.
Pressurized enclosures shall be inspected in accordance with Table 3 of IEC 60079-2 for safety devices
based upon Level of Protection, with standard IEC 60079-14:2013 for Electrical Installations Design,
Selection and Erection and Section, and specifically for action to be taken on failure of pressurization.
If the pressurization control system is fitted with an override device or maintenance switch to allow
the pressurized enclosure to remain energized in the absence of pressurization, e.g. when the
enclosure door has been opened, the continuous flow of the protective gas (air) will continue during
the override.
Override devices shall be used in a hazardous area only if the specific location has been assessed to
ensure that potentially flammable gas or vapor is absent during the period of use (“gas-free”
situation). The enclosure should be de-energized at once if flammable gases are detected while
operating under these conditions and re-purged before it is put back into service.
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