Calibrating Scale / Scale Weights

Calibrating scale testing requirements have become more complex, requiring that the scales survive years of use in rough industrial environments. Ensuring scale calibration is key to extremely accurate and efficient production.

If a scale is not calibrated, it can significantly cost a company financially, and even worse, it can damage its reputation. METTLER TOLEDO’s calibrating scale/test weights are perfectly designed to support testing and calibration of industrial scales. With a strong engineering focus on safe and productive testing, cast-iron weights up to 5 tons are perfect for this application, satisfying even the most stringent testing requirements. For washdown and hygienic environments, high-grade stainless-steel weights are the perfect choice for the best performance. These test weights are available in different shapes and accuracy classes to ensure proper scale calibration and scale recalibration.

1. How do you calibrate a scale?
With large stainless-steel test weights of up to 2 tons, calibration laboratories rely on the exceptional value that our test weights offer. METTLER TOLEDO offers an extensive weight portfolio for the calibrating scale that covers weights from 1 milligram to 5 tons in all accuracy classes. From grip-handle weights to cylindrical weights, each type of test weight offers its own set of benefits during scale calibration and recalibration.

Some grip-handle weights, for example, are ideal for clean room and washdown applications, while others feature welded construction and a glass-bead-blasted, passivated surface that is for heavy-duty operation within harsh environmental conditions. To avoid manual handling operations during scale calibration and scale recalibration, METTLER TOLEDO has designed weights that offer a myriad of lifting options as well. For a calibrating scale job, workers are exposed to certain risks by handling heavy-capacity weights. Some of the design features include 360-degree access by forklifts, cranes and hoists. This helps workers avoid injury by minimizing manual handling hazards during scale recalibration or calibrating scale.

2. What are calibrated test weights used for?
Scale calibration weights are used in scale calibration. This is a process that ensures scale accuracy. Test weights for scales, or precision weights are used to calibrate weight scale systems of various levels of accuracy depending on the use and requirements. Certified test weights should be used in these processes to ensure the test weights are accurate and lead to accurate calibration results.

3. What is the weighing scale tolerance limit of any scale?
This is the required accuracy of the scale, and specifically the tolerance of inaccuracy allowed before it is out of tolerance and in need of a weigh scale calibration by certified calibration weights. A calibrated scale will operate at a higher level of accuracy and maintain tolerance better than not calibrated scales. For this reason, weight scale calibration with certified weights for keeping the weighing scale tolerance limit is key.

4.  What are scale weights?
Scale weights are weights for scale calibration. When calibrating scale procedures are performed, it is necessary to have calibration weights for scales. Weighing scale calibration with scale weights or test weights should be performed on a regular basis depending on use.

METTLER TOLEDO's world leading expertise in metrology extends to certified test weights, weight sets and weight calibration services. The weight portfolio covers scale weights according to OIML or ASTM from fifty micrograms to five tons in all accuracy classes. Our test weights are used all over the world, not only for testing balances but also as primary standards in mass laboratories.

The proprietary electrolytic polishing process for knob and wire weights in the upper class range eliminates microscopic protrusions in the weight’s surface which is far smoother compared to mechanical polishing. Thanks to the enhanced properties of the passive oxide film, long-term stability of the test weight is improved.

5. How do you calibrate a digital scale without weights?
Theoretically, any scale needs a weight to calibrate it and assure highly accurate weighing. If high accuracy is not required, METTLER TOLEDO CalFree can be used to calibrate the scale by using the plant values of load cell and terminal to calibrate. This enables fast and easy calibration to a certain level of accuracy. Additionally, for tank scales RapidCal can be used to calibrate. This is a force calibration method that uses hydraulics to pull down on a tank to calibrate it, rather than using test weights. For a floor scale, typically weights will need to be used.

6. What do you use to calibrate a scale?
Large stainless-steel test weights of up to 2 tons can be used to calibrate scales from small bench scales to large heavy capacity floor scales. METTLER TOLEDO offers an extensive weight portfolio for calibration, covering weights from 1 milligram to 5 tons in all accuracy classes. From grip-handle weights to cylindrical weights, each type of test weight offers its own set of benefits during scale calibration and recalibration.

7. Do you offer calibration weights?
METTLER TOLEDO offers calibration weights in different masses in both OIML and ASTM standards.

8. What are the differences between OIML classes?
The exact difference is explained in the OIML guideline, but at a basic level, E1 has the narrowest and M1 the highest tolerance limit, i.e. E1 is the most accurate.