What must remain attached to the original result?
Keep the test event, equipment identity, procedure revision, original value and original unit together. A converted value is a derived record, not a replacement for the reading actually obtained. If an export omits the unit, ask the test owner for the controlled source rather than infer it from the magnitude.
This original worksheet addresses the comparison step. Calibration records establish instrument evidence, and equipment identity records establish what was tested; neither alone establishes that the result and criterion use the same unit.
How does an absolute temperature conversion work?
NIST Special Publication 811 Appendix B.9 gives the Fahrenheit-to-Celsius temperature conversion as Celsius = (Fahrenheit - 32) / 1.8. The appendix separately lists temperature-interval conversions. An absolute temperature and a temperature difference are different quantities, so do not use one conversion indiscriminately for both.
Commissioning Docs is independent and is not affiliated with NIST. Use the approved reporting precision and technical comparison rule; this guide does not select limits or determine equipment acceptance.
Sources: National Institute of Standards and Technology: NIST Guide to the SI, Appendix B.9
Which fields make the comparison reviewable?
Use a separate row for each result and criterion comparison. Retain the original source file so another reviewer can reproduce the derived value.
| Field | Record | Review control |
|---|---|---|
| Original reading | Value, unit and test record | Preserve exactly what was reported |
| Quantity type | Absolute value or interval | Choose a conversion for that quantity |
| Criterion | Limit, unit and controlled source | Do not invent a limit |
| Conversion | Formula, source and calculated value | Reproduce the arithmetic |
| Precision | Approved rounding or tolerance basis | Keep unrounded calculation available |
| Disposition | Technical reviewer and decision reference | Documentation is not acceptance |
How can an apparent failure be a unit mismatch?
Illustrative example. A synthetic test record reports an absolute temperature of 104 degrees Fahrenheit. A fictional approved criterion is a maximum of 45 degrees Celsius. The conversion is (104 - 32) / 1.8 = 40 degrees Celsius. Comparing the bare numbers 104 and 45 would compare different units. The worksheet records 104 degrees Fahrenheit, the formula and 40 degrees Celsius separately.
The numerical comparison is 40 below 45 under the stated example assumptions. It is not an equipment pass certificate: the responsible commissioning reviewer must also apply the actual criterion, test conditions, measurement uncertainty and required evidence. The example supplies no real equipment limit.
If a revised criterion changes its unit or interpretation, reopen affected comparisons without editing historical readings. Engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Can the original unit be overwritten?
Preserve it and record the conversion separately.
Is a temperature interval converted like an absolute temperature?
No. Confirm the quantity type before selecting the formula.
Does this worksheet approve a test result?
No. Acceptance remains with the authorized project reviewer.
Primary sources
- NIST Guide to the SI, Appendix B.9National Institute of Standards and Technology