Safety managers who run breathalyzers, equipment managers, and staff in charge of submitting certificates face the choice between dry and wet methods when applying for calibration. Dry and wet refer to how the reference gas used for calibration is prepared. The dry method uses a standard gas that mixes alcohol and nitrogen, while the wet method involves a preparation process in which high-purity alcohol is mixed with water and diluted to the standard concentration needed for calibration. The actual conditions of use for the calibration equipment and reference samples must be confirmed within the scope of work of the laboratory you send the device to. Calibration checks the relationship between these references and the breathalyzer's displayed values, and it is distinct from adjustment, which changes the displayed values. Even so, it is hard for the requester to judge suitability from the method name alone.
What matters is whether the method can be applied to the breathalyzer model in question, whether it checks the measuring range used on site, and whether the work is recorded in the certificate you need. Rather than looking for an answer that one of dry or wet is always better, the requester's role is to agree with the laboratory on a scope of work that fits the equipment and the purpose of the document.
Equipment information and request purpose to prepare first
Give the calibration laboratory the breathalyzer's model name, serial number, the test mode and unit currently in use, and previous certificates. Even with breathalyzers from the same manufacturer, you cannot assume every model has the same applicable methods or management conditions. The manufacturer's official Downloads page also provides product-specific manuals and calibration request materials separately, so identifying the model is the starting point of the request.
State where the document will be used from the start as well. The nature of the document and the items it must contain may differ depending on whether you need results for internal equipment management or must submit a certificate to an outside agency. If you ask only for "a calibration completion document," you may have to cross-check again what the actual recipient requires against what the document you received contains.
Questions to ask before deciding on the calibration method
| Question to confirm | Information to give with the request | Answer to obtain |
|---|---|---|
| Can this method be applied to this model? | Model name, serial number, test mode | Whether it applies, and any limiting conditions |
| Which measuring range will be checked? | Unit used on site and required range | Check points and working conditions |
| What result document will we receive? | Whether it is for internal management or external submission | Nature of the document and its entries |
| What happens if results differ? | Abnormal symptoms, previous certificates, repair history | How further checks, adjustment, and repair are distinguished, and the process |
These questions are not meant to rank dry against wet. They are meant to confirm that the work requested, the work actually performed, and the document received match one another. For example, if the laboratory explains that the requested method cannot be applied to the model or needs special conditions, you can go on to confirm how that limitation affects the measuring range you need and the intended use of the certificate.
You can also ask for an explanation of how reference values are managed, but preparing an arbitrary substance yourself and feeding it into the device, or tuning its internal values, is outside the scope of a calibration request. It is better not to mix results of tests improvised on site into the same records as calibration results produced by a professional laboratory under set conditions. When conditions and purposes differ, it is hard to interpret changes in the equipment's condition from the displayed numbers alone.
Why you shouldn't compare numbers on old certificates directly
Just because a previous certificate says dry or wet does not mean you can compare it item by item with the figures on this certificate. Before comparing, look at the measuring range each document checked, the working conditions, and the work stated as performed. A practical approach is to provide the previous certificate at intake and ask the laboratory to separate items that can be compared directly from items that must be read together with their conditions.
As a hypothetical example, suppose a workplace preparing for a periodic inspection is asked to use a different calibration method from before. The person in charge checks the range and work recorded on the previous certificate and gives the laboratory the current equipment's model information and the document content required by the outside recipient. If the laboratory explains that the conditions of the two jobs differ so the figures are hard to compare simply, the observed fact is that "the method and conditions differed," not the immediate conclusion that "the equipment is broken."
A possible action in that case is not to treat the change of method itself as an anomaly, but to sort out separately whether the method applies to the current model and whether the two results can be compared. The completion criterion is not that the past and current numbers match, but that the range checked this time and the purpose of the document are recorded so the next person in charge can understand them too.
Distinguish calibration results, adjustment, and repair
Calibration is the work of checking, under set conditions, the relationship between the values provided by a measurement standard and the values the instrument displays. International metrology vocabulary distinguishes calibration from adjustment of a measuring system and explains that recalibration is usually needed after adjustment. So when you talk with the laboratory, listen for whether the work confirms results compared against a reference, adjusts displayed values, or is a repair addressing a fault.
It is better to report symptoms you know before intake, such as unexpected readings, power problems, or faults in breath sampling parts, together with when they occurred. Writing down which device showed such readings in which situation, rather than just "the values are strange," helps the laboratory consider whether further checks or repairs are needed. Conversely, if you disassemble the inside or change values and then record the outcome as calibration history, later documents can become harder to interpret.
How to carry the received document through to the next request
When you receive the certificate, look at the model you submitted, the method or scope of work you requested, and the work actually performed as stated in the document, side by side. If a different method or additional work became necessary during the job, it is good to keep the reason for the change together with what the document records. Managing the equipment identification, previous certificates, and the purpose of the request at the time as one set, rather than a note with only the method name, lets you re-confirm the same conditions at the next request.
If the purpose is external submission, also check, separately from whether the document was issued by a calibration laboratory, whether it meets the document type and scope of entries the recipient requires. Choosing between dry and wet is not picking a single word; it is connecting equipment applicability, the range checked, and the content of the result document. Asking about these three before you apply lets you define the calibration scope you need more clearly.
