How to Use the Automatic Calibration Feature of Your Precision Balance
How to Use the Automatic Calibration Feature of Your Precision Balance
Obviously you need to calibrate your analytical balance the first time you set it up. However, bear in mind that you are dealing with a very sensitive and precise piece of equipment that can measure mass with a readout of 0.1 mg. Therefore any significant change in the environmental conditions surrounding the balance would require the lab balance to be recalibrated. For example, subjecting the balance to strong vibrations could alter the calibration settings. Moreover, acceleration due to gravity on a mass is not the same at every location on earth and changing the balance location could have an effect on the mass measurement. Note that if you are shifting the balance from a cold area to a warmer environment, it should be allowed to acclimatize for at least two hours before it is recalibrated.
Analytical balances can be calibrated externally or internally, as well as manually or automatically depending on the model. As a typical example of manual internal calibration, let us consider the Kern ABJ analytical balance. This apparatus use an internal calibration weight that is driven by an electric motor to achieve calibration. The user must manually initiate calibration by pressing a button. For an example of automatic internal calibration, let us consider the Kern ABT balance. The balance calibrates itself automatically via the PSC function, using the internal tare weight. It uses a temperature sensor to detect any temperature fluctuation significant enough to influence sensitivity and calibrates automatically if PSC is left ON. Moreover, when the balance is in the weighing mode, automatic adjustment also takes place under the following conditions.
When about four hours has passed since the previous calibration.
When the balance is switched from standby status to weighing mode
When balance is again switched on after being disconnected from the power source.
The weight symbol will flash for about two minutes in order to notify the pending adjustment.
Remember that merely completing calibration does not give you carte blanche to use the balance carelessly. For successful and consistent results, certain precautions should always be taken.
Place the balance on a firm, level surface.
Do not install the balance next to a radiator or in the direct sunlight, to avoid extreme heat and/or temperature fluctuation.
Locate the balance away from open windows and doors, so as to protect it against direct draughts. High humidity, vapors, and dust can also have an adverse impact.
Do not shake or jar the balance during weighing.
Keep the weighing area clean.
Finally, if your establishment has a number of precision balances, it is recommended that you entrust the upkeep and servicing to your metrology group or one of many firms that specialize at this task.