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    User name Jack (Techs)

    Log entry time 23:13:48 on February 14, 2011

    Entry number 346913

    This entry is a followup to: 346904

    keyword=Gas system airflow

    There is a fan in the side of the Gas Shed that has the air compressor. If the wind is just right the airflow slows down and the vane switch in front of the fan opens up and generates a fault. If the wind blows long enough the fault, which turns off the argon and ethane flows, causes the pressure in the gas system to drop low enough that we get a "low pressure" fault. This is essentially a self-latching fault. When this happens someone needs to go out to the Gas Shed and press the "low pressure override" button on the alarm box. The argon and ethane flows should build pressure back up after a few moments and the "low pressure" LED should turn green. Then all should be right in the world. This does not create a problem for the VDCs unless it has been down for a number of hours. Also, the readback of the flows through the chambers will increase differently between the two spectrometers. The Right Arm has bubblers on the VDC exhaust while the Left Arm does not. So, the Left VDCs will show gas flow before the Right VDCs do. The Right VDCs need to build up a little pressure before they start bubbling out the exhaust.