Your Concrete Quality Assurance Plan
For Balances and Scales
Do you know how to ensure that all your balances and scales are reliable enough during routine operation? Do you have an effective and efficient quality assurance plan in place to document reliability and accuracy that considers your individual risk and process requirements?
Our unique GWP® Verification service offers you such a quality assurance plan specifically for your weighing devices. Based on your individualized risk assessment, the service contains your ideal calibration and routine testing plan along with a check that your instrument is fit-for-purpose in terms of accuracy.
The Details of Your Quality Assurance Plan
GWP® Verification, our best-in-class quality assurance plan for balances and scales, contains the following:
- Calibration and service frequency
- Routine testing plan, including the frequency, methods, weights and tolerances
- Fit-for-purpose check on your balance or scale performance (based on a calibration)
Together, these documents create a concrete and audit-proof quality assurance plan for the routine operation of your weighing devices.
GWP® Verification applies to both new and existing balances or scales from any manufacturer in any industry or workplace.
The Benefits of the GWP Approach
GWP® Verification, based on GWP (Good Weighing Practice™) principles, offers you our unique fit-for-purpose check that can be used at balance or scale selection as well as during routine operation. This approach leads to:
- Consistent product quality through reproducible results.
- Reduced material waste and rework costs.
- Audit-proof compliance with appropriate quality management processes.
Routine Testing of Balances and Scales
How can you be sure your weighing results remain accurate between calibrations? Proper routine testing performed by the user gives you both peace of mind and the documentation you need for assurance of ongoing accuracy.
To test your devices properly, test frequency, methods, weights and tolerances need to be defined.
Summary Report and Trend Chart
GWP® Verification includes an assessment for multiple weighing devices and comes with a unique summary report. This report gives you an overview of all your devices at one glance – including potential cost savings or quality improvements in your routine testing.
From your second GWP® Verification onwards, you will receive a trend chart of your weighing devices which allows you to keep track of performance over time. This satisfies the highest demand for documentation, whether you operate one weighing device or many.
1. How often do I need to calibrate my balance and scale?
Calibration is an investigation at a specific point in time and needs to be repeated regularly to ensure continued accuracy over your equipment's lifetime.
The frequency of calibration depends on the use of the device, the environment, and the importance of the weighing results.
To help answer this question, METTLER TOLEDO offers the GWP® Verification service, which gives you an individual, risk-based calibration and service schedule–together with a routine testing plan–to keep your weighing devices accurate over their lifetime and keep your customers happy.
2. How often do I need to perform routine testing on my balances and scales?
The frequency of your routine testing will depend on the risks that are part of your weighing process and how those risks could affect your results.
If the risk to accuracy, your process, or your product quality is high, you will need to perform testing more frequently.
To find out the specific routine testing frequency for your individual process, METTLER TOLEDO offers the GWP® Verification service. This service will define your ideal routine testing plan, including the test frequency, methods, weights and tolerances.
3. How long is a GWP® Verification valid?
GWP® Verification requires an update with every new calibration, change of process requirements, or change in operating environment. From your second GWP® Verification onwards, you will receive the GWP® Re-Verification Report. This includes a trend chart of your balance or scale, allowing you to keep track of the performance of your device over time. This satisfies the highest demand for documentation and is also available for multiple devices (as a GWP® Re-Verification Summary Report).
5. What is the safe weighing range?
The safe weighing range is the range in which the balance or scale gives the most accurate results. This range lies between a scientifically calibrated lower limit (minimum weight determined through calibration) to which a safety margin is added (defined by the selected safety factor) and the maximum limit (capacity) of a balance or scale. Process quality requirements are met if the smallest net weight lies within the safe weighing range.
Since most manufacturers do not declare the lower limits of their devices, it's important to define your safe weighing range.
6. What is the minimum weight?
The minimum weight is the smallest load that can be weighed with a certain balance or scale that still lies within your accuracy requirements (defined by the weighing tolerance in %). It is defined by the relative measurement uncertainty of the device (in %) and your defined weighing tolerance (in %).
7. What is the smallest net weight?
The smallest net weight is the smallest amount of sample mass that the user intends to weigh during the day-to-day usage of the balance or scale; it is a user requirement and not an equipment property. If the smallest net weight equals or is larger than the minimum weight value determined for the required tolerance and safety factor, weighing results adhere to user requirements and are considered accurate.