A legally verified scale that breaks down is usually repaired as quickly as possible. What is often forgotten: after a repair to the weighing system, the legal verification is no longer valid. Before you use the scale again for trade transactions, filling pre-packages or medical weighing, it must be verified again.
In this article you will read which work requires re-verification, how to approach it and what you may do with the scale until then. For the re-verification itself you engage a Recognised Verifier (Erkend Keurder) under the Dutch Metrology Act; see scale verification and re-verification for how that works.
Why a repair invalidates the verification
At the verification it was established that the scale, in that condition, met the requirements for its class. The seals over the adjustment access and the weighing system show that nothing has been changed there since. If a component that determines the weighing result is replaced, or a seal has to be broken to reach the weighing system, that certainty is gone.
That is why re-verification is mandatory before the instrument is used again for legal applications. This also applies if the repair was carried out professionally and the scale appears to weigh perfectly. More about the background in the Dutch Metrology Act and scales.
Which repairs count as repairs to the weighing system?
A repair to the weighing system covers everything that can affect the measurement itself. In practice this mainly concerns:
- replacing or repairing a load cell, even if the new one is identical;
- replacing or repairing the weighing indicator or the weighing electronics;
- adjustment, or changing metrological settings such as the range or the verification scale interval;
- any work for which a seal has to be broken, whatever the reason.
And what usually does not?
Work that does not affect the weighing system and for which no seal is broken does not, as a rule, lead to re-verification. Think of replacing a battery or an external power adapter, or repairing a damaged part of the housing that lies outside the sealed area.
The boundary is not always sharp. If the battery sits behind a sealed cover, or the part of the housing belongs to the sealed construction, the situation is different. Also with a software update of the indicator, repairs to the structure beneath a weighbridge, or a scale that has had a hard fall, the question is not always easy to answer. If in doubt, consult a Recognised Verifier beforehand, so that you do not discover afterwards that the verification has lapsed.
Step-by-step plan for re-verification after repair
- Take the scale out of legal use. Mark it clearly, for example with a label not for trade use, so that colleagues know the verification is not valid.
- Record the repair. Note what was replaced or changed, by whom and when. Keep the work order with the instrument records.
- Collect the instrument data. Make, model, serial number, class, Max, Min and e, preferably with a photo of the type plate.
- Contact a Recognised Verifier. Have it confirmed beforehand that the verifier is permitted to verify your instrument. Why that matters is explained in what is a Recognised Verifier.
- Prepare the scale for the verification. Clean, level, in its fixed place of use and easily accessible for weights and equipment.
- Have it verified. The verifier tests the instrument with calibrated weights, adjusts where necessary and, if the result is positive, applies verification marks and seals.
- Update your records. Enter the verification data in your measuring equipment register, remove the label and release the scale again.
A tip from practice: where possible, have the repair and the re-verification follow on directly from each other. Every day between repair and verification is a day on which the scale is not available for legal applications.
May you use the scale until the re-verification?
Not for legal applications. As long as the re-verification has not taken place, you may not use it for trade transactions, to determine quantities in pre-packages or for medical weighing.
That legal requirement does not apply to internal use, but be cautious. We regularly see a scale that was only supposed to be used internally for a while end up back at the counter. Prevent that with a clear label or put a legally verified replacement scale in its place. If you use the scale internally for quality-critical measurements, first check it with a calibrated weight, because after a repair you cannot be sure that it weighs correctly.
Combining re-verification with a calibration certificate
A re-verification and a calibration answer different questions. The verification says whether the scale meets the legal requirements. The calibration records how large the deviation is, with the measurement uncertainty, as required by ISO 9001, HACCP, BRC and IFS.
After a repair it is often worthwhile to have both carried out at the same time:
- the weights and equipment are already present, so you have one visit and one period of downtime;
- you get a new starting point for the history of the instrument, because results from before the repair are no longer properly comparable;
- you record the deviation across the range with measurement uncertainty, which a verification itself does not provide.
If the scale was still being used for quality-critical measurements before the repair, also ask for results before adjustment, if these could be measured. With those you assess whether earlier measurements may have been off. How to read such a certificate is explained in calibration certificate explained. What else you record when a measuring instrument deviates can be found in the measuring equipment management checklist.
How MASSLAB helps you
MASSLAB is a Recognised Verifier and carries out re-verifications of legally verified scales after adjustment or repair. Beforehand we check, on the basis of make, model and serial number, whether we are permitted to carry out the verification for that specific instrument. Adjustment, re-verification and a calibration according to EURAMET cg-18 can be done in one visit, on site or in our laboratory. More information under scale verification and re-verification and on-site calibration.