Tank Scale Calibration for Accuracy and Traceability

Test weight calibration is the most accurate method, offering accuracy of 0.03% or better. This method entails adding certified test weights to the scale and taking a reading for each successive weight that is added, taking piping effects into account. It requires the ability to hang or place weights on the tank system, and is typically limited to tanks scales up to 2t (5klb).

This method is theoretically unlimited in capacity, but is somewhat cumbersome and time consuming. For larger scales, it may be impossible to hang test weights equal to the full capacity. In these cases, we use a combination of test weights and an inert material (such as purified water) to calibrate and adjust the scale, the method also takes piping effects into account. The need for calibration material may cause high calibration costs and due to incremental errors, this method is typically between 0.03% and 0.1% accurate.

RapidCal™ Calibration offers many benefits, it is fast, does not require any test weights or calibration material, thus eliminating the waste of purified water. A sophisticated hydraulic system is used to apply the test load, measuring precisely to desired references while also accounting for piping effects. The achievable accuracy is 0.1%, which is viable for most tank scale applications. RapidCal requires specific anchor points at the tank scale and the foundation, consult METTLER TOLEDO for more details.

When traceability is not required, CalFree™Plus is an ideal method of tank calibration. The system is able to automatically calibrate itself with just a few commands. The method transfers factory calibration error-free to the site, but cannot account for other influences like piping. Thus, it is difficult to predict the achievable calibration accuracy.

Note: Any weightless calibration method without regular re-calibration cannot alert to calibration errors over time. Use these methods only if the possibility of measurement errors are not of high importance.