Instrument calibration and documentation process map

What is in this map

14 steps across 3 swimlanes and 6 phases, with 2 decision points.

Swimlanes (who does the work)

ServiceDesk, Calibration Lab and QA & Documentation

Phases (left to right)

Intake, Preparation, As-Found Calibration, Adjustment & Re-Test, As-Left Calibration and Certification & Release

Why map this process

The as-found reading is the entire point of a calibration certificate, and it is also the easiest step to skip under time pressure, because logging a number before you have fixed anything feels like nothing has happened yet. This map puts 'record readings before any adjustment' in its own row, ahead of the tolerance decision, specifically so it cannot be quietly folded into the adjustment step. A certificate with no as-found value cannot tell a customer whether their instrument had actually drifted, only that it is correct now.

The traceability of the reference standard is the second thing a rushed calibration loses, and it fails silently: nothing about a bad reading looks different from a good one if the equipment it was measured against had itself gone out of date. Putting 'verify reference/standard equipment is traceable and in-date' as its own step before any reading is taken is what stops an expired reference from quietly invalidating a whole day's certificates.

Every step in the map

This is the spreadsheet behind the diagram. The numbers in “Goes to” are row numbers, which is exactly what the editor’s “Line to” column holds — so you can read the flow here and retype any part of it.

The decision points

Every branch in the map, with the label on each outgoing line. These are the questions the process has to be able to answer.

• 6. Within **tolerance**?

  Owned by Calibration Lab · As-Found Calibration

  • Within tolerance → step 11
  • Out of tolerance → step 7

• 9. Re-test within **tolerance**?

  Owned by Calibration Lab · Adjustment & Re-Test

  • Within tolerance → step 11
  • Still out of tolerance → step 10

Notes on specific steps

These notes travel with the map. In the editor they live in the Notes column and appear when you open a box.

1. Work order received

The work order specifies the instrument(s), whether the job is a site visit or a lab drop-off, and which standard the certificate must be issued against (in-house method or full DANAK / ISO 17025 accreditation).

3. Verify reference/standard equipment is traceable and in-date

The reference standard must carry its own valid calibration certificate, traceable to a national metrology institute, and must not fall due for its own recalibration before this job closes out. An expired reference invalidates every reading taken against it.

4. *As-found* calibration: record readings before any adjustment

Logged exactly as measured, before anything is touched. This is the value that proves whether the instrument held its accuracy since the last calibration, and it goes on the certificate even when the instrument turns out to need no adjustment at all.

10. Hand off to Out-of-Tolerance Calibration SOP

An instrument that still fails acceptance criteria after adjustment leaves this SOP here. Deviation assessment, customer notification and the repair/replace decision are handled under the Out-of-Tolerance Calibration SOP, not repeated in this one.

11. *As-left* calibration: record final readings

Recorded and put on the certificate whether or not any adjustment was made. An instrument that already passed as-found still gets an as-left entry, so the certificate always shows both values side by side.

12. Issue **calibration certificate** and documentation

The certificate carries the as-found and as-left readings, the reference equipment's own traceable calibration data, and the accreditation reference (DANAK / ISO 17025) the lab operates under.

Making it yours

The tolerance decision after as-found calibration is a single Decision row with two branches in the Line text column: 'Within tolerance' skips straight to as-left calibration, 'Out of tolerance' routes through adjustment and a second, identical decision after re-test. When you adapt this map, keep both tolerance checks as separate rows rather than merging them — the second one is what decides whether the job stays inside this SOP or hands off to a different one entirely.

What to watch out for

• Do not skip the as-left reading when as-found already passed. An instrument that needed no adjustment still gets an as-left entry on the certificate, recorded in its own row here, because the certificate's value is showing both numbers side by side, not just the final one.
• The 'still out of tolerance after re-test' branch is a hand-off, not a dead end. This map ends that path at a Reject box pointing to a separate out-of-tolerance SOP rather than looping the adjustment step again, because deviation assessment and customer notification are a different process with a different owner.
• Do not let the certificate step absorb the accreditation reference as an afterthought. The map's final documentation row names the standard the lab is certifying against (an in-house method versus full ISO 17025 accreditation) as data on the certificate itself, decided back at intake — retrofitting it after the job is done is how a certificate ends up making a claim the lab cannot back up.

Frequently asked questions