Thermo Scientific SOLA II, Руководство пользователя

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Thermo Fisher Scientific SOLA II User Guide G-1
Appendix G
The X-Purge System
The X-Purge assembly is used to provide safe operation of analyzer systems in
Class 1, Division 1, Groups B, C, and D (NFPA) and Zone 1, Ex d[p] IIC T4
(ATEX and IECEx) hazardous areas. Safe operation is achieved by
automatically disconnecting power from the analyzer system if the purge
pressure is lost in any of the monitored enclosures or if purge flow out of
either enclosure exhaust port is lost. The X-Purge system also ensures that the
system is safe before it permits power to be applied to the analyzer system.
To ensure continued safe operation of the analyzer system, the X-Purge unit
must not be disabled or adjusted improperly.
On power-up, the X-Purge system checks the purge pressure in all monitored
enclosures and for flow exiting the exhaust ports of the enclosures. When all
monitored enclosures register pressures at least
0.3 inch of water (0.75 mbar) above the reference pressure, adequate flow is
present at the enclosure exhaust ports, and the instrument air pressure is
greater than 10 psig, a time delay relay begins its timed cycle. Typically, the
time delay is used to ensure that at least four volumes of air are exchanged in
the enclosures before power is applied to the system. (The number of
exchanged volumes may be higher in some situations.) After the preset time
delay is accomplished, the time delay relay applies power to the analyzer
system.
Typically, the X-Purge assembly is designed for monitoring two enclosure
purge pressures and two exhaust port flows. All of the pressures in the
monitored enclosures must be at least 0.3 inch of water (0.75 mbar) higher
than the atmospheric pressure around the analyzer system. This ensures that
hazardous materials are less likely to leak into the purged enclosures. Pressure
differential switches compare the pressure in the monitored enclosures with
the pressure in the explosion proof X-Purge enclosure. The inside of the X-
Purge enclosure is referenced to ambient pressure using a 1/4-inch breather
drain with flame suppression. A flame arrestor is also installed between each
pressure differential switch and the associated pressure enclosure that it
monitors. A spark arrestor vent is used for exhaust purposes. It also maintains
appropriate backpressure on the electronics enclosure and oven.
Description