We supply Class F weight sets with all of our Computrac® moisture analyzers for balance calibration. Since customers occasionally have questions regarding the specification differences between Class F and Class 2 weights in the calibration of analytical balances, we have provided this brief explanation.
Internally, our staff uses Class 1 and Class 2 weight sets to calibrate and verify the operation of each unit prior to shipment. Typically, though, Computrac® moisture analyzers are found on the production floor where they are operated and maintained by production personnel. Class 2 weights, which require special handling by trained individuals, do not encourage operational checks on the floor. Class F weights, on the other hand, promote the frequent checks necessary for accurate and reliable results, while providing tolerances that exceed our own specifications. They are a convenient, economical and easily handled alternative.
The Class F 3g and 5g weights supplied with all Computrac® moisture analyzers are to be used as a calibration check only. This check tests the accuracy of the balance in measuring proportional weight changes. The tolerance for the weight test using the 3g and the 5g Class F weights is 37.50%, ± 0.02. In order for the weight test to be out of tolerance due to inaccuracies in the weights, the weights would have to vary more than 1.5mg from the 3g or 5g nominal value. Class F weights are rated to within 0.5mg of the nominal value. For the 20g calibration of the internal balance, the Class F weight has a tolerance of 0.8mg, this exceeds our internal specification of 20g ± 3.0mg.