Glossary · Batch and process operations
Unit procedure
German: Teilanlagenprozedur
In ISA-88 batch control, a unit procedure is a strategy for carrying out a contiguous process within a unit. It consists of an ordered set of operations that cause the contiguous production sequence to take place within that unit.
- Batch control
- Process industry
- Standards
In one sentence
In ISA-88, a unit procedure is the strategy for a contiguous process within one unit, made up of an ordered set of operations.
Example
The unit procedure on the dryer consists of the operations "load", "dry under vacuum" and "discharge".
How it applies
- Engineering: Only one unit procedure is normally active in a unit at a time; the batch system allocates the unit for its duration.
- Operation: The transfer of material between units usually marks the boundary between two unit procedures.
- Batch records: Records group data per unit procedure, showing which unit processed which part of the batch.
- Documentation: Process descriptions per unit procedure should cover start conditions, operations, end conditions and material transfers. Consistent names across recipe editor, HMI and SOPs help operators and reviewers.
Unit procedure vs. operation
A unit procedure covers the entire contiguous processing of a batch in one unit. An Operation (ISA-88) is one independent processing activity within it.