Laboratory scales are very precise instruments and they must be well-maintained to ensure they give accurate and reliable readings.
It is vital that all lab scales are kept in good working order at all times and checked regularly to ensure that they do not give inaccurate results or have developed faults.
Calibration is an essential part of this maintenance procedure. It should be done at time intervals to suit the lab and reflect the level of use the scales get. Laboratory scales that are used very often by different scientists, or those that need a very high level of accuracy and reliability, should be calibrated more often than those which are used infrequently or that do not need to give very accurate readings.
Before starting the calibration procedure, the lab scale should be clean and free of all dirt or debris. Even the smallest particles of dust can affect the readings and will mean calibration is not accurate and future results cannot be relied on.
Environmental conditions should also be stable for the same reasons. The temperature, humidity and airflow should be within pre-determined limits so as not to affect the process.
The operator manual will give the exact instructions for calibration, but the general procedure starts with zero-ing the balance.
It will then ask for a calibration mass to be placed on the bench, which will allow the lab scale to reset itself to the known mass.
The lab scale calibration procedure ensures scientists get accurate and reliable measurements and will allow the lab to meet the required quality control standards.