Understanding Calibration Weights

Calibration weights are essential tools for achieving high precision and accuracy in various measurement tasks. These weights allow for the calibration of different scales and instruments, ensuring they provide reliable results. In industries ranging from pharmaceuticals to engineering, having the right calibrated weights for scales can significantly enhance outcome accuracy.

Weight classes established by the American Society for Testing and Materials (ASTM) range from Class 0 to Class F. Each serves a specific role depending on the sensitivity and requirements of the equipment. (The International Organization of Legal Metrology [OIML] has its own classes of calibration weights.) By understanding the nuances of these weight classes, users can better appreciate their importance in maintaining stringent quality controls.

Choose the Right Calibrated Weight for Your Needs

Selecting the appropriate calibrated weights for your scales involves more than picking a random weight; it requires careful consideration of your specific needs. Start by identifying your scale's maximum capacity and then choosing a weight class that complements this capacity to ensure accuracy. Certified calibration weights for digital scales provide an additional layer of reliability and assurance, making them a preferred choice for many professionals.

Here are a few key points to keep in mind:
• Weight Class: The class of the weight affects its precision level; the lower the class number, the higher the precision.
• Material: Weights made from stainless steel or cast iron offer durability and precision.
• Certification: Certified scale weights for calibration come with a guarantee of accuracy and traceability.
• Compatibility: Ensure the weight is compatible with your specific type of scale.
• Usage Frequency: Consider how often you will use your calibrated weights, as this might affect the type of weight you choose.

METTLER TOLEDO Test Weights - Five Do's and Don'ts for Proper Weight Handling

The way you manage, clean, and store calibration weights significantly impacts the continued accuracy of your weighing operations. Calibrated weights are essential for testing and calibrating scales and balances and necessitate careful handling.

FAQs About Calibration Weights

Calibration weights play a vital role in ensuring the accuracy of various measuring tools, but there are often questions about their use and maintenance. Here are answers to some of the most common questions to help you get the most out of your scale calibration weights:

What Is the Difference Between Certified and Non-Certified Weights?

Certified weights have been verified for accuracy by an authoritative body and come with documentation detailing their calibration. Non-certified weights are generally used for routine checks where high precision isn't critical.

How Often Should I Recalibrate My Scales?

You should recalibrate your scales at least once a year or more frequently if they're used heavily. This ensures continued accuracy and performance

What Are the Benefits of Using Grip-Handle Weights?

Grip-handle weights allow for easier handling and reduce the risk of dropping, which can damage precision instruments.

What is NIST?

NIST stands for National Institute of Standards and Technology, and is a division of the United States Department of Commerce. The NIST makes regulations that manufacturers must follow to ensure industry standards. When purchasing NIST weights or weight sets you are being assured that your weights have been tested to meet their standards. NIST weights are most commonly used for commercial and legal for trade scales.

What is NVLAP?

NIST also runs the National Voluntary Laboratory Accreditation Program (NVLAP). This program evaluates and accredits laboratories in their respective fields and ensures they meet ISO standards

What is ASTM?

ASTM stands for American Society of Testing and Materials. The ASTM is an international organization that establishes and develops methods for testing materials. ASTM weights and weight sets are made to the tolerance, construction, finish, and magnetism set by them. ASTM requires that weights be made of one piece (no fillers or air to compensate for small adjustments). ASTM weights are recommended for calibrating other weights or high resolution balances

What is OIML?

OIML stands for Organization Internationale de Metrologie or better known as The International Organization of Legal Metrology. OIML is an international organization that sets guidelines for legal metrology. (Metrology involves measurement, measurement devices, and procedures.) OIML guidelines encompass everything from how the weights are manufactured to how they are to be used in calibration procedures.

What is a traceable certificate?

Many weights and weight sets are available with traceable certificates as an additional option. These certificates are issued by laboratories and manufacturers that are accredited by NIST/NVLAP, ASTM, and/or OIML depending on the type of weight, manufacturer, and class.
These certificates are traceable to NIST and contain information such as type of weight, weight class, density, uncertainty, and environmental conditions at the time of calibration

What is a certificate of calibration or Accredited Certificate?

This report is similar to the traceable certificate however it will have a smaller uncertainty and more precise values. This has to do with the methods involved as well as the number of times the tests are repeated.

What is a traceable mass value report?

This report is traceable to NIST and reports the actual weight values, tolerances, and uncertainties. However the ratios reported are not guaranteed and is not considered an accredited document.

What is a certificate of accuracy?

A certificate of accuracy is not accredited or traceable. This report is required to be completed to NIST standards and will have an NIST report number. This report will contain the weight or weight sets serial number, description, nominal value, class and tolerance.

Do I need a certificate for my weight(s) or weight set(s)?

This depends upon your needs and requirements. You need to check with your governing agency, quality control department, or product literature. Usually if dealing with ISO-9000 requirements you will need some form of an NIST traceable certificate

What class weight/weight set do I need?

• Class 0, Class 1, E1, E2- These weights are the most sensitive and accurate. These require clean environments and special handling. These classes would be used to calibrate Class I/II balances, balances accurate as 0.001mg, and as a laboratory standard. These classes are considered to be of extra-fine accuracy.
• Class 2- This class is considered to have a fine accuracy and designed for Class II balances. This class would be recommended for balances that are as accurate as 1mg.
• Class 3- Recommended for analytical balances as accurate as .01g.
• Class 4- Recommended for semi-analytical balances accurate to 0.1g. These are ideal for balances in school laboratories and industrial settings.
• Class5, Class 6, and Class 7, Class F- These classes would be ideal for industrial and harsh environments. These are most often used for scales used in the home and production settings.

Find the Best Calibration Weights at Scales Galore

Explore our extensive selection of calibration weights and find the perfect match for your needs at Scales Galore. Whether you're in a laboratory setting and looking for calibration weights for a digital scale or you need scale calibration weights for heavy-duty industrial applications, we have something to suit every requirement. Find yours today!