What Is ‘Calibration’ and How Does It Differ From Adjustment?
Calibration is a term historically associated with the balance adjustment process. It means determining the deviations of a measuring instrument. Before calibration, the balance is in the reference position, adjustments are made (if possible) and then the systematic error and random error of the balance are determined. Calibration results are given together with the uncertainty of their determination.
Adjustment, on the other hand, is a set of activities through which a measuring instrument is made to operate in accordance with its intended use. In the case of electronic balances, the device’s sensitivity is corrected by comparing the weighing result of the internal adjustment standard with its reference value.
Types of Adjustment (Calibration):
- Automatic internal adjustment – controlled by temperature and time changes
- Manual internal adjustment – carried out by means of an internal adjustment balance’s button
- External adjustment – performed using an external mass standard of a declared mass, which cannot be modified.
Note! External adjustment is possible for balances which are not a subject to conformity assessment (verification).
Internal Adjustment (Calibration)
The process is fully automatic and requires no intervention from the operator. If the weighing pan is loaded, a message will appear on the display instructing the user to remove the load. If the load on the weighing pan is small (up to approx. 4% of the balance’s maximum capacity), automatic adjustment will still take place, but the weighing results will differ by the mass of that load.
External Adjustment (Calibration)
The process is carried out by the operator using an external mass standard, the value of which is stored in the balance’s factory menu. This function is not available on balances which are not a subject to conformity assessment (verification).
Internal Adjustment (Calibration) – Is It Worth Paying Extra for?
Internal adjustment takes place automatically, meaning it does not require operator intervention. This translates into savings in time and labour, and furthermore, the process carries no risk of human error. If the balance is to be used in an area where weighing results have legal or financial implications, it must be verified, which means it must have internal adjustment. This applies, amongst other things, to areas such as:
- Trade and retail
- Taxes, customs duties, fees and penalties
- Medicine and pharmacy
- Courts, experts and administration
- Laboratories.
In summary, internal adjustment is a feature worth paying extra for.
