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    User name Jack (Techs)

    Log entry time 12:11:53 on November 09, 2008

    Entry number 247759

    This entry is a followup to: 247730

    keyword=Gas system shutdown

    The nitrogen in the gas system ran out around 6AM. At that point the pneumatic valves lost pressure and closed. Eventually the pressure bleeds down in the argon and ethane lines and the VDC system will give a "low pressure" alarm. While all the cylinders that were changed were empty, what caused the trouble was that BOTH of the nitrogen cylinders ran out. When they are replaced the NITROGEN PURGE VALVE needs to be opened temporarily to charge the pneumatic valves. Once the pneumatic valves are functional the bypass valve should be closed and one of the nitrogen cylinders selected to be online. This was done around around 9AM. The only system this might be an issue for is the VDCs. The ethane takes longer to bleed down than the argon. I see in the Archiver that the argon and ethane mixing was shut down during this time except the ethane was flowing from about 8:00 to 8:30, but no argon. So, there may be a little change in the VDC operation. Flow was on and back to normal at about 9AM.