Professional scenario conversions
Migrating legacy industrial units
Legacy plants still reference psi, HP, and °F alongside SI in modern SCADA. Migration projects need conversion tables, alarm threshold revalidation, and operator retraining—not only software upgrades.
Immutable raw historian values plus derived SI columns preserve both safety audits and analytics.
Key takeaways
- Export tag lists with engineering units before PLC edits.
- Recompute relief and interlock setpoints from first principles after unit changes.
- Parallel old/new displays during bake-off to catch alarm drift.
- Supplier acceptance tests: write SI equivalents beside imperial clauses.
How to convert
100 psi = 6.89476 Bar
Inventory every sensor unit
Export tag lists with engineering units before touching PLC code so nothing is assumed.
Parallel run periods
Run old and new unit displays side by side during a bake-off window to catch mismatched alarms.
Safety interlocks
Pressure relief and temperature trips must be recomputed from first principles after unit changes.
Maintenance manuals
Translate spare part torque specs and lubrication intervals with the same revision control as code.
Supplier contracts
Performance tests referencing imperial units need explicit SI equivalents to avoid acceptance disputes.
Legacy HMI screenshots
Training slides photographed from old panels may show obsolete units—date-stamp every screenshot in the knowledge base.
Spare parts interchangeability
A “same” motor with different frame dimensions in mm vs inch can fail mechanically; verify mounting patterns after conversion.
Calibration certificates
Third-party labs may report in mixed units; map certificate rows to PLC engineering units in a single lookup table.