Reposition the batch

The initial location of the batch fragments after a pipeline has been loaded is set by the Controller using the editing facilities. Location is then updated on each processing cycle in the following steps.

1. At an upstream terminal for the pipeline, volume of batch flowing into the pipeline since last processing is determined, using information from the Metering-Ticketing application.

2. The volume of batch is added to the segment at this location. This volume may be added to the existing fragment or a new fragment may need to be created if the batch has changed.

3. The total volume in the segment after the addition is calculated and compared to linepack.

4. The amount of volume exceeding linepack is removed from the fragment at the downstream end of the segment and made available to the next segment downstream.

5. At the next downstream segment, the volume arriving from upstream is added in the same way as it was from Metering-Ticketing as in step 2 and the process continues as above.

6. When volume is removed from the final segment, it disappears and no further accounting for it is done.

7. In the unusual case that total volume in the segment is less than the linepack, then volume is brought back from the next downstream segment. If this is the final segment, volume is added to it so that total volume is equal to the linepack. Volume of fragments equal to calculated linepack is always maintained.

8. Flow cannot move into a segment that has a closed valve. There are two complications to the above steps: segment merges and segment splits.