Scale Inspections 

In Arizona, Weights and Measures Services Division (WMSD) investigators regularly conduct inspections of scales used to determine the direct cost of commodities bought and sold. There are over 21,000 scales licensed with our agency, and these scales vary in size and design.  For example, you  might find us testing a small metric scale used to weigh precious metals at a pawn shop, or perhaps the deli scale at your local grocery store. We even have equipment to test large capacity scales such as platform scales at recycling yards and vehicle scales installed at truck stops. Big or small, we ensure that all commercial scales are accurate, suitable for use, properly installed, and legal for trade.


Scale Accuracy

In regards to accuracy, minor, seemingly insignificant errors can add up. Assume a scale used for weighing cheese has an error of one-hundredth of a pound (displayed as 0.01lb on a scale indicator). If you average 100 weighments on this scale daily for 365 days, at a unit price of $7.99 per pound, the total resulting error would be $2,916.35 for the entire year, based on one scale. If you consider that there could be similar errors on any other scale at the business, the monetary gain or loss could drastically impact the consumer or the business.

The only way to know if a scale has an error is to perform a full test of the device. Most scales we license are tested up to their marked capacity using known test weights that are traceable to a NIST-certified metrology laboratory (like our State Metrology Lab). Some larger capacity scales must only be tested up to 50% or 25% of their marked capacity. Our requirements for commercial scales and associated test procedures and user requirements are adopted directly from NIST Handbook 44, and are part of Arizona state law as outlined in A.R.S. § 3-3413. In addition to scale accuracy, there are many other requirements that a scale must meet to ensure that it will continue to operate accurately and cannot be used to facilitate fraud. 

WMSD has the authority to issue enforcement action for scales that do not comply with Arizona regulations. Enforcement tags may be attached to scales by a WMSD Investigator if an official test results in one or more violations. A red "Out of Service" tag may be issued for scales that exhibit abnormal performance or have errors in favor of the device owner/operator. A yellow "Warning" tag may be issued for violations that do not directly affect the scale's accuracy, or for scales that have errors in favor of the consumer. Red tag violations must be corrected by a licensed Registered Service Agency (RSA) before the scale can be placed back into service. Yellow tag violations generally provide a timeframe for the device owner/operator to correct a violation while still allowing continued use of the scale. WMSD may also issue a blue "Stop-Use" tag to any scale that is not legal for trade or not suitable for use. A blue tag generally prohibits all future commercial use of a scale. However, WMSD may allow a scale that was not suitable for use in a particular commercial environment to be moved and used commercially in an environment better aligned with the scale's capacity and design. 


Not Legal for Trade/NTEP

A common area of non-compliance in regards to scales is "not legal for trade" devices. Often, we find that device owners will purchase a scale from a distributor or online source, and believe that the scale is acceptable for use in commercial applications. When we arrive at their business to inspect the scale, the device owner may be surprised to find out that the scale they thought was acceptable is actually not legal for trade. As a result, WMSD takes enforcement action which subsequently removes the scale from commercial service through a Stop-Use order (blue tag), and the scale may even be seized by the investigator as evidence.

Our goal is to prevent not legal for trade scales from entering the marketplace. We understand that a scale is an investment, and we want to help businesses understand scale requirements before they unknowingly purchase a non-compliant device. So, what makes a device legal versus not legal for trade in Arizona? Arizona Administrative Code R3-7-203 requires that any commercial device installed or placed in use after January 1, 1975 have a National Type Evaluation Program (NTEP) Certificate of Conformance. These programs put commercial devices through repetitive tests in various environmental conditions to ensure that they have the ability to operate accurately and prevent the facilitation of fraud through their design. If a device passes this series of tests an NTEP Certificate of Conformance (C of C) is issued. Modern weighing and measuring devices are required have an NTEP Certificate of Conformance approval number marked on the manufacturer's ID plate. This number will often be preceded by "NTEP CC", "CC", or "Approval No.", and the number generally consists of two digits denoting the year of approval followed by a dash and three numbers (e.g.. 04-019).

Many scales that are not legal for trade are marked either near the indicator or on the manufacturer's ID plate with the text "NOT LEGAL FOR TRADE" or similar verbiage. This is a red flag right away that your device should not be used commercially. Scales manufactured prior to January 1, 2003 may not be marked with an NTEP approval number. This does not necessarily mean that the scale is not legal for trade. The scale may not be marked with this information because it was not required at the time it was manufactured. In this case, please contact WMSD directly at 602-542-4373 or [email protected] to determine if your scale is legal for trade. If you know the make and/or model of your scale, you may also search for a Certificate of Conformance on the NTEP website.


Buyer Beware!

WMSD has come across scales in commercial use that appear to have the manufacturer's markings of a legitimate "legal for trade" scale, but upon further investigation do not have an NTEP Certificate of Conformance. Many of these scales looked similar to actual legal for trade devices, almost as if they were counterfeit versions of a legitimate device. Again, if you are unsure about a scale you wish to purchase, please contact WMSD for further assistance.


Scale Licensing

For information regarding commercial device licensing, please click here.

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