SGP/ACSM/C1 - Instrument inlet pressure low
|DataStreams:||sgpaosacsmcalC1.b1, sgpaosacsmC1.b1, sgpaosacsmC1.00, sgpaosacsmC1.01, sgpaosacsmC1.a1|
The pressure at the inlet to the instrument was at least 100 torr below ambient after work was performed on the vacuum line serving the ACSM. The inlet pressure also dropped from 1.3 torr to approximately 1 torr. Examination of the data during reprocessing shows that aerosol loadings during the period specified are unreasonably low and suggest that the instrument was not sampling ambient air. The data for the specified period are unreliable and should not be used. I visited SPG to perform ACSM tuning and calibration on 2015-10-06. While there I measured the flow in the line bringing sample to the ACSM. The flow was > 45 lpm. This high rate was pulling a vacuum on the ACSM sampling line. The vacuum was high when the cyclone was in line upstream of the ACSM and was the cause of the low pressure seen after the changes to the system were made in August. The flow past the ACSM inlet should be 3 lpm. The inlet pressure was ~700 torr when it should be ambient. I disconnected the sampling line from the Gast vacuum pump and reconnected and connected it to the Aerodyne pump which is part of the dryer system. The flow rate is now 3 lpm, the ambient pressure 740 torr, and the inlet pressure 1.3 torr. The instrument was calibrated and is now performing properly.
Do not use the data during the specified period.