8.2 Sample flow (purge flow)

The flow path of the At-Line Sampling Module is as follows - 


Sample flow path superimposed on rear of the At-Line Sampling Module

  • If no split or make-up flows are used (see nest section), then the sample flow is the total flow through the At-Line Sampling Module and the Lonestar. The pressure of the sample flow is set by adjusting the inlet pressure to the Lonestar, and the flow rate is set by adjusting the needle valve on the exhaust of the Lonestar. The flow rate and pressure at the detector are displayed on the dashboard of the Lonestar software.
  • Clean air leaves the Lonestar via the port labelled Clean Air Out. This air has travelled through the Lonestar’s integral scrubber and then through a length of PTFE tubing within the body of the Lonestar.
  • The sample flow then travels into the At-Line Sampling Module at the left. It flows through the dip tube and into the headspace of the glass sample bottle. Here, the clean, dry air picks up analytes and water vapour from the sample.
  • The sample flow then passes along the first heated sample transfer line, through the particulate filter and along the second heated sample transfer line. The flow carries the analytes into the Lonestar detector.
  • After passing through the detector, the air flow exits the Lonestar at the port labelled Exhaust.
  • Caution! The exhaust flow should always be vented appropriately. If toxic or harmful compounds are present in the sample, the exhaust flow must be vented into a fume hood.
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