Legal-for-trade balances and scales undergo more rigorous testing than a common scale or balance and must successfully pass all tests to achieve legal-for-trade certification. Legal-for-trade scales and balances are sealed at the point of manufacture to prevent unauthorized access to internal components, help businesses pass audits by Weights and Measures inspectors, and give buyers confidence that the weighing equipment has not been tampered with.
Legal-for-Trade Scales And Balances
Weighing on Approved Instruments in Commercial Transactions
What does "Legal for Trade" mean? Why is it important in commercial transactions?
Business transactions where price is determined by mass demand accuracy with approved equipment. Use of legal-for-trade scales and balances ensures consumer protection, the customer receives the amount of goods they pay for, as well as fair-trade, preventing financial loss for businesses.. Legal-for-trade scales and balances undergo rigorous testing to meet stringent legal metrology requirements, helping to protect your customers and your business, whether you are a retailer or wholesaler.
The leading standards for legal-for-trade scales and balances are the recommendation R76 issued by the International Organisation of Legal Metrology - OIML, and the Handbook 44 of the National Institute of Standards and Technology - NIST.. However, legal requirements for weighing equipment vary between countries, and wholesalers and retailers must ensure that they fulfill local regulations. METTLER TOLEDO approved scales and balances are designed and manufactured to meet local metrology guidelines.
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How Are Legal-for-Trade Balances and Scales Unique?
Types of Legal-for-Trade Balances and Scales
Legal-for-Trade Jewelry Balances
Gold and Diamond Scales for Accurate Jewelry Weighing
A jewelry balance is a device designed to accurately weigh diamonds, gemstones, gold, silver, and other precious metals. Our jewelry scales and balances are made of high quality materials and have overload protection to ensure reliable performance...
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Legal-for-Trade Laboratory Balances
A Wide Range of High-Quality and Accurate Laboratory Balances
Lab balances are highly accurate weighing instruments that measure the mass of a sample with a very high degree of precision. They are available with capacities from 1.2 g up to 64 kg and readabilities ranging from 0.0001 mg (7 decimal places) to ...
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Legal-for-Trade Bench Scales
Certified Trade-Approved Bench Scales for Selling Product by Weight
Legal-for-trade bench scales are tabletop weighing scales which are rigorously tested and certified for use in business transactions where products are sold by weight. Trade-approved bench scales are required to ensure fairness to both buyer and s...
See full descriptionNTEP Bench Scales
Accurate Weighing for Industrial and Commercial Use
NTEP (National Type Evaluation Program) bench scales are tabletop scales that have been tested and certified by the National Institute of Standards and Technology (NIST) to meet specific standards and guidelines for accuracy, repeatability and oth...
See full descriptionRelated Content and Answers to Most Common Questions
Avoid Serious Pitfalls when Applying Legal Metrology Rules
Legal metrology aims to ensure fair trade and protect financial transactions, setting strict rules for weighing large amounts where the capital involved is significant. However, these strict rules do not apply to in-process environments in which smaller quantities are being weighed, such as laboratories or production areas. In these environments, only adhering to legal metrology rules may compromise quality because the maximum permissible error is relatively high for very small weights.
Legal metrology requirements and internal accuracy requirements have different purposes and should be used in combination. Relying on only one set of requirements may lead to poor quality or non-compliance of legal requirements.
FAQ - Legal-for-Trade Weighing
What is the difference between "legal for trade" and "non-legal for trade"?
Legal-for-trade balances and scales must be used when mass determines the price in a business transaction. For example, the price of a gold necklace depends directly on the mass of gold it contains. Conversely, when tracking how much of a diamond has been polished away, a legal-for-trade scale is not required. While still very important for the business, this mass measurement is not part of a sales transaction.
My jewelry scale is calibrated once a year when it is serviced. But how often do I need to test it in between?
The frequency of testing required in between depends on the accuracy that you require, the environmental conditions and the associated risks during measurements. Higher accuracy requires more frequent testing. However, JET scales feature internal weight and FACT technology, which adjusts the scale automatically. When using FACT, the amount of testing can typically be reduced. Contact us for precise advice on testing balance and scale.
Why does a legal-for-trade scale cost more than a regular scale?
To qualify for "Legal for Trade", there are many extra requirements that a scale must fulfill over and above the requirements of a regular scale. For example, the additional software adaptations necessary will require extra investment for the manufacturer, adding to the price of the scale. The extensive conformity assessment that every legal-for-trade scale undergoes, and the required associated documentation for the approval, also contribute to the additional cost.
Do I need to have my legal-for-trade weighing instrument calibrated by a service technician?
A calibration performed by an authorized service technician is always recommended to ensure passing the legal verification by Weight & Measures officers.
Through normal use, the performance of a weighing instrument will change over time. Calibrating a scale or balance once per year by an authorized service technician is always a good idea to maintain a documented record of its performance.
Is an approved balance or scale better than a regular one?
METTLER TOLEDO balances and scales are all produced to consistently high-quality standards.
A legal-for-trade weighing instrument is not necessarily better than a regular one. It will depend on the accuracy of the instrument and its maintenance. A legal-for-trade instrument, however, ensures the fulfillment of minimum accuracy requirements and is subject to periodical inspections by Weight & Measures authorities. These are the reasons for the mandatory use of legal-for-trade weighing instruments for commercial transactions to protect consumers and ensure fair trade.
What is the difference between 'approved' and 'legal-for-trade' balances?
An “approved” or “verified” balance or scale is a weighing instrument which has been tested and certified by a competent authority to meet specific accuracy and reliability requirements for legally relevant applications including trade, safety, health, and environment.
Colloquially the term “legal-for-trade” associated to a scale or balance is expressed with the meaning of an approved weighing instrument used for trade, i.e. for commercial transactions.
What do e=d and e=10d mean?
d – actual weighing instrument interval - is the smallest division that a balance or scale can display.
e - verification weighing instrument interval - is the smallest interval on a balance or scale that is allowed to be used in a business transaction.
For example, a scale has d = 0.001 g, providing weight results to three decimal places. In the case that e=d, the scale can be used in business transactions measuring weight to three decimal places (0.001 g). In the case that e = 10d, the scale can only be used in business transactions measuring weight to 10 x 0.001 g = 0.01 g.
Why does my legal-for-trade scale show the last digit in brackets?
When the e value of the scale is greater than the d value (see previous question), the digit(s) in the weight result that cannot be included in a business transaction are shown in brackets.
My scale has d = 0.01 g. Does this mean I can weigh 0.01 g on it?
A weighing instrument with d =0.01 g can´t weigh a total mass of 0.01 g accurately. Every mass measurement made on a balance or scale has a degree of uncertainty. When the item being weighed is very small, the error due to the measurement uncertainty becomes large compared to the mass of the item. Every balance has a point below which the uncertainty is so high that the weight results cannot be deemed to be accurate. This point is known as the minimum capacity. It is the smallest weight that you can weigh on your balance or scale with acceptable accuracy. This value is mandatory for a legal-for-trade weighing instrument. For a regular weighing instrument, the service technician can determine during calibration the minimum capacity required by customer´s requirements. If the customer requires a higher degree of accuracy, the minimum capacity must be increased (this reduces the level of uncertainty).
Where can I find out if I need a legal-for-trade or a regular scale?
Contact your local METTLER TOLEDO representative to get a direct and personalized recommendation. You can also check your local Weights and Measures authority, or contact your country's Trading Standards office. They can help you determine if you need a legal-for-trade balance or scale. The OIML recommendation R76 or in the US, the NIST Handbook 44, provide guidance.