subject: Fundamental Concepts of Calibration of Analytical Balances [print this page] The process of calibration establishes a relationship between an input and an output quantity under specified lab conditions. Analytical balances are characteristic examples of direct calibration where the value of the standard, also referred to as the reference value' has the same expression of magnitude as the weighing equipment that is used in the experiment. Both the analytical balance as well as the reference value is expressed in the standard units of mass.
Reliable and sound analytical measurements are important for successful lab experiments. Accurate weighing is essential in labs and medical establishments. For example, the quantity of medication that is to be administered to a patient or determining contaminants in water need calibrated analytical balances. The equipment used for analytical weighing must meet all standards and specifications.
The fundamental concepts of calibration of analytical balances involve using a test weight that allows the analytical balance to calibrate itself. The balance first needs to be set to a base point of zero for accuracy. From this starting point, the maximum load that the balance can take can be calculated. The range of weights, starting from zero to the full capacity weight of the analytical balance defines its span.' The advantage of accurately measuring the span of the analytical balance is that it calibrates the balance and makes it possible to measure an entire range of weights starting from the base point of zero to the total capacity or span.
Most analytical balances also have certain additional features that allow lab personnel to tune the equipment for weighing test substances with greater accuracy and reliability. This is possible by calibrating the balance using weights that are below the maximum weighing capacity of the balance. Lab personnel may use the equipment according to their personalized and customized weighing needs.
Whatever be the requirement, using test weights is the best way to ensure accurate calibration. If an analytical balance is calibrated using certain specified test weights whose weight lies in the range of the experimental substances that are to be weighed, the balance displays better and more accurate results as it is using a well-defined span of its weighing capacity. This process of manual and customized calibration is extremely useful in analytical experiments.
There are certain environmental factors like temperature, pressure and humidity, air currents and gravitational acceleration that may affect the process of calibration. It is recommended to calibrate the analytical balance during the process of installation, before using it for each and every weighing experiment and this becomes even more important when the balance is moved to another space or location in the lab. Calibration must be carried out using a wide array of test weights and lab personnel must have access to these weights at any given point in time. The availability and use of the right kind of calibration mass is extremely important. Ideally to ensure accurate weighing results buy the calibration weights along with the analytical balance itself. Also, if you have many different types of analytical balances, tag the test weights for easy identification.
Fundamental Concepts of Calibration of Analytical Balances
