When you receive a calibration certificate and try to transfer its values to a site checklist, different units make it hard to tell which side is right just by looking at the numbers. A breathalyzer is a device that measures a breath sample and displays a result, and a calibration certificate is a document recording the values a specific device showed during calibration. Site records are often forms built for daily checks and reporting, so they may not use the same units as the certificate.
What you need here is not to convert the numbers quickly into a familiar format, but to confirm what each record refers to. Read the certificate's measurand, unit, and conditions first, match them one by one to the items on the site form, and record a converted value separately only when its basis is confirmed. Following this order reduces the risk that a unit difference changes the meaning of the original result.
Find what the certificate measured before reading the numbers
The first thing to look at on a certificate is not the number field but the measurand the number represents. Whether it records the relationship between the reference value and the device's indication during calibration, or the result shown on the device screen, determines which field on the site record it should be compared with. ILAC-G24:2022/OIML D 10:2022 also addresses reading calibration results together with the relationship between the reference value and the instrument's indication.
Next, read the unit symbol on that row together with the value as one unit. If you copy only the number, the link between the decimal places and the unit is broken. Also review the conditions stated on the certificate and the uncertainty shown with the result, without separating them from the same row. Uncertainty carries a different meaning from the result value, so it is better not to write it into the measured-value field on the site form.
How to compare the original and the site form side by side
Even if an item name on the site form looks similar to the wording on the certificate, do not assume right away that they mean the same thing. Check whether the value the site form asks for is the device indication, the reference value, or a notation set for reporting. If the internal form only has a unit printed on it and no record of the basis for that unit or a conversion rule, do not arbitrarily change the certificate value to fit that field.
Comparing the original information and the internal record separately, as below, makes clear what needs to be checked. The purpose of the table is not to impose a new form. It is to let anyone tell the certificate value apart from a value recalculated at the site.
| Item to compare | What to read on the certificate | What to keep in the site record |
|---|---|---|
| Meaning of the measured value | Whether it is the reference value or the device indication | Which item on the site form it corresponds to |
| Unit and value | The original value including the unit symbol | The original unit and the transcribed value |
| Calibration conditions | Conditions stated with that result | Whether the conditions allow direct comparison |
| Conversion | Rule confirmed by the calibration body or internal standard | Conversion formula, who confirmed it, and the date confirmed |
If the form is electronic, the automatic calculation features also need checking. If changing the unit setting recalculates earlier entries under the new rule, it becomes hard to trace back the original value on the certificate at the time. It is useful to separate the original value, the converted value, and the reason for not converting into different fields or with clear labels.
Convert only when there is a confirmed rule
Different units are not always resolved by simply moving the decimal point. First determine whether the units look different because of a simple notation difference or because of a difference in the measurand or the applicable conditions. If you only match the number of digits without checking this, you may end up presenting the rewritten value as if it were the certificate's original result.
As a hypothetical example, suppose a safety manager wants to transfer a certificate result to the site's monthly checklist. The certificate lists a reference value and a device indication separately, and the checklist has a single result field with only a unit written on it. The fact this manager should observe is that "there are two numbers," and the problem to interpret is that it is unclear which of the two the checklist asks for.
In this case, a possible action is to keep each value and unit on the certificate as in the original, and to check the checklist's instructions or the display description for that device. User manuals for each device are available in the product materials in DATECH's official Downloads center, so do not guess the current device's units from a screen photo of another model or from memory. Treat the record as complete when the value the checklist asks for corresponds to the certificate value and the basis for the conversion rule is confirmed. Until then, keeping the value in the original unit with a label such as "conversion basis unconfirmed," instead of a converted value, avoids distorting the result.
Distinguish the roles of manufacturer information and calibration results
The screen display and unit descriptions in a user manual help you understand in what format a device shows its results. A certificate, on the other hand, contains the results a specific device showed during calibration. So the general display guidance in a manual does not replace that device's calibration results, and a single result on a certificate cannot tell you how other models display results either.
Even with the same model name, the materials you transcribe must be that device's certificate and that model's documents. Especially when collecting device records from several sites, it is a good idea to first survey which units and item names each site currently uses. Only after preserving the originals should you set the notation rules for shared reporting, so that past records can be explained later.
After transcribing, you must be able to trace back to the original
If values were entered by hand, you can have another person compare them against the original certificate. In doing so, check not only the numbers but also the measurand, unit symbol, decimal position, and whether a conversion was made. This second comparison is not a new assessment of the device's accuracy. It is a search for transcription errors that can occur when records are moved.
Keep the certificate file or paper original linked to the site checklist. If there is a converted value, record the conversion formula and the date the rule was confirmed, and do not overwrite the original value. When you later need to submit the certificate or explain the numbers on a past checklist, being able to tell which value is the original and which was prepared for internal reporting keeps the records reliable even when the units differ.
