GE Analytical Instruments ©2006 13-12 DLM 14291 Rev. A
• Slowly unscrew the cap on the top of the purge vessel to release any
pressure that might have built up during the purging.
• To drain the reducing agent, open the drain stopcock (CAUTION: HOT
HYDROCHLORIC ACID).
To refill the purge vessel with fresh reducing agent:
• Close the drain stopcock, add 4-5 mL of VCl
3
/HCl and 100 µL of dilute
antifoaming agent.
• With the Outlet stopcock closed, replace the screw cap and open the gas
inlet stopcock. Gas will begin to flow into the purge vessel
• Since the gas bubbler is still connected to the NOA, it is under reduced
pressure. If the outlet stopcock on the purge vessel is opened rapidly, the
NaOH will bump into the IFD filter. If the stopcock is opened slowly, the
NaOH will not bump.
• Slowly open the outlet stopcok while watching the level of the NaOH.
The NOA signal will initally increase with fresh VCl
3
/HCl, but the signal will
return to baseline after a few minutes.
Opening the Gas Bubbler
The gas bubbler containing NaOH is also under a vacuum and if not opened
properly, the NaOH can backup into the tubing to the purge vessel. To open the
gas bubbler:
• Close the outlet stopcock on the purge vessel, leaving the stopcock on the
bubbler open.
• Loosen the 1/4” nut on the Swagelok union connected to the outlet of the
purge vessel.
• Once loose, slowly
pull the union off the purge vessel while keeping an eye
on the level of NaOH in the bubbler. As the union is removed, air will be
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