Purge the System

When changing the gas that is flowing through the analyzer, or when the type of gas connected to a port is changed, purge the analyzer of the previous gas by flowing the new gas. The system should also be purged if the loop is changed.

If changing gases during an analysis, allow the new gas to flow for a period of time before creating conditions that cause the experiment to begin (such as elevating the temperature). In some cases, purge one gas by flowing an inert gas for a period of time before starting to flow another gas. This may be useful for avoiding undesirable combinations of gases within the analyzer.

To flow an inert gas between incompatible gases, insert a Change Gas Flows step (in which an inert gas is flowed for a period of time) and a Wait step (to wait for the inert gas to purge the analyzer) between other steps that involve incompatible gases.

 

When gas flows are changed while the analyzer is recording data, the gas flow is briefly disturbed. This may result in a brief period of noise or other visible disturbances on the peak data. Either disregard the disturbance or insert a Wait for stable baseline step immediately after changing gas flows.

 

Purge one line at a time. It is the operator’s responsibility to ensure that dangerous combinations of gases are not created while using Manual Control. It may be necessary to flow an inert gas through the system between flows of incompatible gases.

  1. Go to Unit [n] > Enable Manual Control. Ensure a checkmark displays to the left of the menu item. If the analyzer schematic does not display, go to Unit [n] > Show Instrument Schematic.

  1. Set the Cold Trap valve, Analysis valve, Loop valve, and Detector heat zone temperatures to 110 °C.
  1. Right click the valve’s heat zone (the cursor will change to a thermometer) and right-click.
  2. Select Set temperatures and enter 110.
  3. Click OK.
  1. Wait until the temperature reaches the 110 °C target. On the right side of the schematic, click the heat zone to display both the target and current temperatures.
 

When the heat zone is clicked, the cursor appears as a thermometer. If the valve is clicked instead, move the cursor slightly and click again.

  1. Purge all air from the preparation gas line.
  1. Right click the preparation gas Mass Flow Controller (MFC).
  2. Select Set flow rate and enter 50.
  3. Click OK.
  4. Right click the four preparation gas valves.
  5. Right click the Flow Gas [n] selection to open the valve that corresponds to the gas to be purged.
  6. Allow the gas to flow for approximately 20 minutes or until the lines have been purged of air.
  1. Repeat step 4 for each valve that has a gas cylinder connected.
  2. Repeat the process (steps 4 and 5) for the carrier and loop gas flows.

Change the Gas Flow During an Analysis

When changing gases during an analysis, allow the new gas to flow for a period of time before creating conditions that cause the experiment to begin (such as elevating the temperature). Purge one gas (by flowing an inert gas for a period of time) before starting to flow another gas. This may be useful for avoiding undesirable combinations of gases within the analyzer.

To flow an inert gas between incompatible gases, insert a Change Gas Flows step (in which an inert gas is flowed for a period of time) and a Wait step (to wait for the inert gas to purge the analyzer) between other steps that involve incompatible gases.

  When gas flows are changed while the analyzer is recording data, the gas flow is briefly disturbed. This may result in a brief period of noise or other visible disturbances on the peak data. Either disregard the disturbance or insert a Wait for stable baseline step immediately after changing gas flows.
 
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