K - Time, time schedule
Reference for the ISA 5.1 first letter K. K shows up most often on drawings that pre-date the PLC era. Hardware timers and sequencers used to earn their own tag because they were physical relays you could point at. Modern PLC code does the same job invisibly. The K tags you still find on a 1985 drawing are usually batch-step sequencers or interlocking timers that have either been migrated to code already or are running on the original equipment for the next 20 years.
Read one of your own drawings.
Drop a P&ID, instrument index, or schedule. Tagsight reads it to the tag and opens a workspace you keep when you sign in.
PDF · DWG · DXF · TIFF · PNG · XLSX
Also stands for.
- Time-rate of change
Common second letters.
Computing element, KY. Timer or sequencer
Indicator, KI. Time indicator
Example tags.
Time-based computing element, often a sequencer step
Typical placement.
On batch operations and sequence-driven processes. Most modern P&IDs do not carry K-prefix tags because timing logic lives in the PLC code rather than as a discrete drawn instrument.