The balance
Calibration of balances
Any balance will only give correct results if it is checked regularly, i.e. calibrated correctly and adjusted when required. A balance is only a reliable measuring and checking tool if it is calibrated and this calibration is documented. The issued DKD calibration certificates are proof of the metrological traceability to national and international standards, as required by the DIN EN ISO 9000 and DIN EN ISO/IEC 17025 standards, amongst others. KERN recommends a recalibration period of one year.
DKD Initial and recalibration of balances (independent of brand) at the KERN factory
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Initial and recalibration of balances (independent of brand) at the KERN factory Weighing range |
KERN |
Price € excl. of VAT ex works |
|---|---|---|
| Analytical balances/Precision balances | ||
| Max ≤ 5 kg | 963-101 | 125,- |
| Max > 5 kg | 963-102 | 160,- |
| Precision balances/Industrial scales | ||
| Max ≤ 5 kg | 963-127 | 65,- |
| Max > 5 kg – 50 kg | 963-128 | 80,- |
| Max > 50 kg – 350 kg | 963-129 | 95,- |
| Max > 350 kg – 1500 kg | 963-130 | 150,- |
| Max > 1500 kg – 2000 kg* | 963-131 | 200,- |
| Max > 2000 kg – 6000 kg* | 963-132 | 400,- |
|
Preparation for recalibration (cleaning, adjustment, function test) |
969-003R | 20,- |
| Additional services: | ||
| Minimum weight of sample | 969-103 | 10,- |
|
Digital calibration certificate (by e-mail as PDF file) |
969-102 | 5,- |
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DKD express service with 1 day delivery time (only on new purchases) |
962-116 | 50,-/parcel |
|
Express shipping: Express supplement for guaranteed delivery on the next working day (if ready to send before 12.00 noon) |
on request |
*only floor scales
As a customer you have the following options: Calibration at the KERN factory
(you send your balance to us)
Recommended for new devices and for balances which can be affordably transported, as then there is no need for us to travel to carry out the calibration on-site. Repairs can be carried out at the same time, quickly and in full.
The process would be as follows:
Day 1: Send your balance to the KERN calibration laboratory in Balingen. Days 2 to 3: Evaluation and calibration of your balance by our specialists. Day 4: After positive validation, your balance is returned.
KERN on-site calibration
(we visit you)
In Germany, KERN has a close-knit network of KERN DKD calibration laboratory employees, who can carry out on-site calibration of balances up to 6 tonnes. This KERN calibration service is also independent of the brand. Preparatory maintenance work by agreement. Prices for on-site calibration on request.
You tell us when you would like us to come, giving us details of the balances to be tested. Our on-site DKD calibration team will then get in touch with you immediately and will discuss the process with you - it's straightforward and professional.
Minimum weight of sample
What is the lightest item you can weigh on your balance, while still achieving accurate and reliable weighing results? What exactly is the limit?
The KERN minimum sample weight protocol accounts for the established minimum sample weight of your measuring equipment and its location of installation and use, with the relative measuring uncertainty – and with various safety coefficients and required weighing accuracy (process accuracy), depending on standard or quality-related requirements on the balance being used.
The higher the selected safety coefficient, the higher the safety when using the balance in a particular process. Typical perturbations when using the balance e.g. small fluctuations in temperature are taken into account. In easily predictable conditions in a professional environment of use, KERN recommends a safety coefficient of 3. For critical processes, a correspondingly higher factor should be selected.
The minimum sample weight protocol contains a diagram as well as a table, from which you can ascertain the minimum sample weight for your balance, depending on the process.
Example:
The operator requires a 1% process accuracy (of the weighing value) on his balance. With a selected safety coeffi cient of 1, the minimum sample weight according to the table would be 0.0098 g. With the same process accuracy but with a safety coefficient of 5, he may not weigh any items under 0.0491 g on the balance.
Usage accuracy
As the calibration of a balance is a snapshot, there must be a statement relating to how the measuring instrument behaves in operation in the location of use, or to what extent the measuring uncertainty may change.
This is because with daily use, the measuring uncertainty of a balance increases due to various infl uences. These influences must be recorded and rated ...
… and this is how:
By accepting that the same environmental conditions (e.g. draughts, vibrations, …) as they were at the point of calibration are present at the location of the balance and estimated room temperature fluctuations of X Kelvin (°C) with a temperature coefficient assigned in the balance (X.10-6/ K), the result is a particular accuracy of use. You can establish this accuracy of use in accordance with EURAMET/cg-18.