Is Your Scale Fit for Purpose?
How do you know your scales are fit for purpose? You know that you need to weigh to a particular capacity and resolution. You might also know what manufacturing tolerances you need for that process. But how do you know which scale is right for the job? METTLER TOLEDO’s Good Weighing Practice or GWP system can help determine whether you have the needed scale.
Good Weighing Practice or GWP is a methodology that considers several factors influencing weighing accuracy. Accuracy and readability are not the same things. Accuracy describes how close a measurement is in relation to the true value. Scale maximum capacity, minimum capacity, processing tolerances, and environmental conditions like temperature, all contribute to a scale’s suitability for a task. GWP analyzes these factors and helps you pick a scale that will give accurate weighing results and help you fulfill your requirements effectively.
Accurate Weighing Results in 3 Simple Steps
Evaluation and Selection
If you are looking to purchase a METTLER TOLEDO device, we can take your base information like maximum capacity, smallest net weight, weighing tolerance, and safety factor, and produce a recommendation report that shows which scale would be fit for purpose. The report includes the recommended minimum weight for that scale to reproduce accurate results.
Installation
Brady Systems can provide a variety of installation options utilizing METTLER TOLEDO’s installation Pacs. Products include the StarterPac, IPac, and AccuracyPac (Installation & ACC calibration) These products provide professional installation and qualification and provide audit-proof documentation.
Calibration
Calibration is a vital part of any weighing program. It should be performed at the location where the scale is used. Depending on your needs, there are a variety of options for scale calibration.
- Basic calibration
- Comprehensive Test Report (CRT) – provides a thorough assessment and documentation of the weighing performance to confirm the proper operation of the weighing device according to OIML/HB44 legal for trade tolerances
- Accuracy Calibration Certificate (ACC) – Delivers a calibration certificate with measurement uncertainty according to international guidelines. Confirm weighing performances according to your process or OIML/HB44 tolerances.
- ACC ISO17025 accredited – Provides calibration of your weighing device in compliance with local ISO17025 accreditation standards.
GWP Recommendation
GWP recommendation makes it easy to choose the right equipment. It documents that the equipment meets your specific accuracy and process requirements. Using four requirements for your weighing process, GWP ensures the consistent quality of your products and saves you on material, waste, and rework.
- Maximum weight – Specifies the capacity of your weighing equipment
- Smallest weight – Specifies the minimum weight of your weighing equipment
- Weighing tolerance – Limits the maximum permissible error (measurement uncertainty) of the device
- Standards and regulations – Ensures that the device will meet relevant quality standards (such as legal for trade, ISO, USP, etc.)
Using the 4 pieces of information you provide on your requirements, the GWP recommendation summarizes your weighing needs in one piece of documentation. It is an easy way to ensure that the equipment you purchase will be fit for purpose. This recommendation is provided by Brady Systems free of charge. Just ask your sales representative to include it with the proposal.
GWP Verification
GWP verification is a service provided by METTLER TOLEDO and Brady Systems after the installation of your equipment. The GWP verification report provides a risk-based individual calibration and routine testing plan. This defines the frequency, method, weights, tolerances, and standard operating procedures (SOPs) for routine testing, along with the ideal service schedule. This ensures consistent quality for your product and saves you money on material, waste, and rework.
Available for any type of weighing equipment, the GWP verification report provides information on:
- Pass/fail statement to a tolerance
- Minimum weight determined
- Fit-for-purpose statement
- Safe weighing range
- Risk-based calibration and maintenance plan
- Risk-based routine testing plan
The GWP verification report is based on a completed ACC calibration certificate. Talk with your local sales representative to learn more about GWP verification and how it can help you ensure that your weighing devices are fit for purpose.
