What should be considered when determining calibration frequency is the value of the product that is being weighed, ISO or your Quality Policy, number of weighments per day, if the scale is being moved from location to location, legal-for-trade applications, environment, and the percent of scale capacity that is being used.
Value of Product: Eliminating any errors on the scale would save a great deal of money and avoid penalties from erroneous weights from freight companies.
ISO or Quality System: Your company Quality Policy may dictate your frequency of calibration. Failure to comply with your quality policy could result in loss of accreditation.
Number of Weighments: Obliviously the more the scale is used even a tiny error will add up.
Moving Scales: A scale may not be required to be in a permanent, but if not moved correctly, to maintain accuracy would need to be calibrated on a regular basis.
Legal for Trade: Local or state Weights and Measures inspectors can shut down your production if your scales are found to be out of tolerance.
Environment: is the weighing being done in a dry dust free environment or is it a wet, dusty, weighing corrosive product, exposed to weather, etc.
Scale Capacity: Scales that are being used at or near capacity will require frequent calibration because of the deflection of the load cells (if electronic) or wear spots on pivots and bearings if mechanical.
As you can see Frequency of calibrations depends on a number of factors. The recommended frequency is below:
- For extreme use or where weighing accuracy is critical the recommendation would be a 30 day cycle.
- In most cases having your scales calibrated on a 90 day cycle is would be the recommendation.
- For scales in a clean dry environment 180 days cycle would be the recommendation.
- Scales that are in a clean dry environment and have few weighments per day a cycle of 365 days would be the recommendation.