How to calibrate an electronic balance

Electronic balances are a familiar, cornerstone object in all laboratory settings.  They are a widely used tool throughout education, particularly in the Science Curriculum, and they can vary in capacity, readability and price.

Electronic balances do not require specialist servicing, but may need to be calibrated from time to time, in order to maintain their effectiveness and lifespan.

Calibrating an electronic balance ensures the reliability and repeatability of students weighing results and maintains its accuracy.  Reliability and repeatability are important up to GCSE Level, whereas a balance's accuracy is more important for A-Level and beyond. 

Calibration involves checking the reading given on the balance against standard known-mass calibration weights.  Most electronic balances in an educational setting require Span Calibration, which involves calibrating the balance at two points on its scale.  These are usually zero and maximum capacity.

When to calibrate a balance

• On delivery. Your balance may have been travelling over a large distance in different modes of transport to get to your school or laboratory. The internal calibration could have been disturbed during transit. The balance may have also been through changes in gravity which can also disturb the initial internal calibration done by the manufacturer.
• Calibration once a month should be ample for general educational balances.
• For more advanced practical work involving precision balances, these should ideally be calibrated each time they have been moved to a new location or laboratory.

Electronic balances must always be calibrated according to the manufacturer’s instructions. Some may need specific types of weights in order to calibrate them.

Other manufactures may include an auto-calibration function with their balance, so it always worth checking the model instructions included with your electronic balance before starting.

Steps to calibrating an electronic balance 

• Turn on the electronic balance
• Ensure it is levelled and stable; and is placed away from any draughts
• Enter the balance into Calibration Mode (instructions for this will be found in the product manual). ‘CAL’ is usually shown on the screen to show the calibration mode is active.
• Select Span Calibration (as per the manufacturer instructions)
• Zero the balance (this may need to be done twice in some cases until ‘--C--' appears).
• The balance will usually display the weight of the mass required to calibrate.
• Add the appropriate mass onto the pan of the balance, wait for the reading and the calibration is complete.

How to prolong the lifespan of an electronic balance

• Regular cleaning
• Storage. If balances are not described as stackable, they must not be stacked on top of each other during storage
• Balances should be protected from humidity, dust, corrosion, vibration
• Electronic balances must not to be stored or operated near to any strong magnetic or electromagnetic fields
• Avoid spills – students should be taught to report any spills onto balances in the classroom so that they can be cleaned immediately
• Objects must not be dropped onto the pan

Learn all about calibrating an electronic balance

The Philip Harris specialist team are here to help with any technical questions you have calibrating electronic balances, or any other support you need. Call them on 0345 120 4521 or e-mail techsupport@philipharris.co.uk. 

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