Converting RBDs to PFS Diagrams

You can convert an existing simulation RBD to a PFS diagram that reflects the throughput properties and connections specified in the original RBD. It is also possible to copy blocks from a simulation RBD and paste them to a PFS diagram.

To convert the RBD, open the diagram and choose Diagram > Conversion > Create PFS Diagram.

A PFS diagram with the same name as the RBD but with "_pfs" appended will be added to the project.

The following rules apply to the blocks during conversion:

  • Only the Throughput, Throughput unit and Allocation properties are converted; Send units to failed blocks and the backlog-related properties are ignored.
  • Standard blocks and nodes are converted to process blocks. However, if the first word in the block’s comments is "tank," the block is converted to a tank block.
  • Containers are converted to subdiagrams. For each container block in the original RBD, a new RBD is created (named using the pattern RBDname_cnt_ContainerName). In the converted PFS diagram, a subdiagram block that references this new diagram is created. Note that in PFS diagrams, subdiagrams that reference RBDs have the same throughput properties as process blocks (and failure/maintenance properties are derived from the blocks in the corresponding RBDs).
  • The maximum throughput for every connector in the PFS diagram is calculated based on the RBD block’s Throughput property and its specified allocation type.
  • For process blocks, the coefficients used in the mass balance equation are calculated based on the previously calculated maximum throughput of each input and output connector. The coefficients are calculated such that the sum of input coefficients is equal to the sum of output coefficients and also reflect the allocation type of the original block in the RBD.
  • For tank blocks, if the original block used the equal allocation type, the tank block uses Equal++; if the original block used the weighted allocation type, the tank block uses Weighted++.

  • In the converted PFS diagram, a source block is created and connected to the first found starting block unless that starting block does not have a URD; in this case, the block itself is converted to the source block.

  • In the converted PFS diagram, a sink block is created and connected to the first found ending block unless that ending block does not have a URD; in this case, the block itself is converted to the sink block.

The conversion process may result in the creation of multiple diagrams. Specifically:

  • As noted above, for each container block in the original RBD, a new RBD is created (named using the pattern RBDname_cnt_ContainerName). In the converted PFS diagram, a subdiagram block that represents this new diagram is created.
  • If the original RBD has a subdiagram block that represents another RBD:
    • If that subdiagram block has the Use throughput properties as defined at this level option selected, then the subdiagram block that is created in the converted PFS diagram represents that existing RBD subdiagram.
    • If that subdiagram block has the Use throughput properties from blocks in the subdiagram option selected, then the RBD subdiagram is also converted to a PFS diagram. In the main converted PFS diagram, the subdiagram block that is created references that new PFS subdiagram.

    Note: If the RBD that you are converting has any subdiagram blocks that represent fault trees (or if any of its subdiagrams do), conversion will not be possible.

    A Note About Copy/Paste

    When copying blocks from a simulation RBD to a PFS diagram, there are a few differences from full diagram conversion:

    • No diagrams are created even if you copy/paste a subdiagram block. The pasted subdiagram block will always represent the existing RBD subdiagram regardless of the Use throughput properties… option selected in the original subdiagram block in the RBD.
    • No source or sink blocks are created/converted.
    • Container blocks cannot be pasted.

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