Determine temperature and pressure values for a segment

To calculate the average temperature for a segment, the system needs to use the temperature value at the upstream end of the segment and the temperature value at the downstream end of the segment. The following search algorithm is used to find these values.

The logic described in this section also applies when calculating average pressure.

Upstream search

To determine the temperature at the upstream end of the segment (for example, point X at the upstream end of segment S3 in the diagram below), conduct an upstream search as follows:

1. Use the temperature analog configured for the upstream end of the segment. If a temperature analog was not configured, proceed to the next step.

2. Starting with the segment directly upstream of the current segment, use the temperature analog configured for the downstream end of the segment (2a). If this is not available, use the temperature analog configured for the upstream end of the segment (2b). If no temperature analog is found, proceed to the next step.

3. Move to the next upstream segment and perform a similar search downstream (3a), then upstream (3b). Continue the search in upstream segments until a temperature analog is found. If no temperature analog is found, proceed to the next step.

4. Use the base temperature value configured for the segment.

   

Downstream search

To determine the temperature at the downstream end of the segment (for example, point X at the downstream end of segment S2 in the diagram below), conduct a downstream search as follows:

5. Use the temperature analog configured for the downstream end of the segment. If a temperature analog was not configured, proceed to the next step.

6. Starting with the segment directly downstream of the current segment, use the temperature analog configured for the upstream end of the segment (2a). If this is not available, use the temperature analog configured for the downstream end of the segment (2b). If no temperature analog is found, proceed to the next step.

7. Move to the next downstream segment and perform a similar search upstream (3a), then downstream (3b). Continue the search in downstream segments until a temperature analog is found. If no temperature analog is found, proceed to the next step.

8. Use the base temperature value configured for the segment.

   

   Notes: If a temperature analog has the auto-inhibit path configured, the value of that path is used to determine if the analog point can be used during the upstream or downstream search. If the analog is auto-inhibited, the search algorithm will consider it as non-existing.

   If a temperature analog is flagged as being in test mode or instrument fail mode, the search algorithm will consider it as non-existing.