Posts Tagged ‘analytical balance’
Selecting Scale Weights for Calibration Testing
Calibrating precision digital scales, analytical balances and moisture analyzers that rely on accurate weight measurement requires periodic tests using a scale weight closely matching the maximum capacity of the instrument being tested.
Why Testing with Scale Weights is Important
Daily we depend on weighing accuracy – such as visits to the deli counter in the supermarket. We want assurance that the weight shown on the scale is accurate. The U.S. Government’s Weights and Measures Division sets the guidelines.
But in research labs and in food, drug and other production facilities, weighing accuracy assumes a highly critical criterion. This applies to weighing and measuring instruments where readout (the smallest weight difference displayed) and linearity (the ± deviation from the actual weight) are governed by GLP, ISO and other standards.
Adding to challenges, the accuracy of precision weighing and measuring instruments can be … Read the rest
How to Use an Analytical Balance: 5 Tips
University and industrial laboratory researchers requiring extremely accurate measurements of extremely small quantities rely on a precision instrument called an analytical balance. Shopping for an analytical balance requires being familiar with some of the advanced features available today as well as the proper use of these precision instruments. It is on the second point that we focus this post on how to use an analytical balance.
Here you will learn
- How to set up an analytical balance
- The effect of environment on weighing accuracy
- How samples can introduce errors
- The importance of personal practices
- Important maintenance tips
Tips for Analytical Balance Weighing Accuracy
Accuracy is a prime if not the prime criterion for analytical balances used in industries such as researching and compounding pharmaceuticals. Analytical balance weighing accuracy is a measure of how close the displayed weight is to the actual weight of samples on the weighing pan.
Two terms apply here. The first is readout, which is the smallest difference in weight that can be read and displayed by the unit. For an analytical balance it is typically 0.1 milligram or 0.001 g. Micro and ultra microbalances can weigh lighter samples.
Accuracy is sometimes confused with precision but it is an incorrect assumption. Precise means that results are consistent. However they may be consistently wrong, and therefore not accurate.
Instead, the second term or criterion to look for is linearity. Linearity is the maximum ± deviation of the displayed sample weight vs. the actual sample weight over the weighing range of the … Read the rest
Internal vs External Analytical Balance Calibration
Calibration is a procedure intimately associated with analytical balances. Calibration determines the relationship between the displayed value and true mass by comparison with a known mass. In other words, calibration determines the accuracy of an analytical balance or precision scale.
Suppliers of analytical balances and precision scales such as Tovatech have sources that provide calibration services and certificates for newly purchased equipment. Good laboratory practices, good manufacturing practices as well as conformance to several published regulations call for regular recalibration of these instruments and adjusting them if required. To accommodate this manufacturers such as Kern offer analytical balances and precision scales with automatic internal calibration and adjustment (if needed) or external calibration and manual adjustment.… Read the rest