Legal trade and non-legal trade scales both have regulations and rules at the manufacturing level, and each has its potential upsides and drawbacks to discuss before purchasing, calibrating, or re-calibrating them. But how do they affect you? Position Partners tells about the difference between legal and non legal trade scale calibration.
Legal trade scales or ‘trade-approved’ scales are industrial scales used to determine how much someone pays. This can be in a commercial setting, or to calculate a tax, toll, remuneration, bonus, tariff, or penalty. If you are using a scale for this purpose, or for lawmaking or medical purposes, trade measurement law dictates that you must use a legal trade scale.
These are scales that could have detrimental effects on the general public if inaccurate.
Legal trade scales have certain requirements and regulations that non legal trade scales do not. To get a scale trade-approved, a seller must get it certified by an NMI inspector, who will evaluate it on its design, marking requirements, environmental factors, and operation including in different temperatures. They may conduct shift tests, increasing and decreasing load tests, and test the scale over different temperatures, to determine whether it is suitable for trade.
Legal trade scales are issued with an approval number and must maintain their accuracy, so the NMI requires legal trade scales to be reverified after alteration or repair.
Weighbridges must be re-verified after 12 months, but there is no legal requirement for other scale types to be verified after a certain time. However, it is recommended that owners of industrial scales of any type get their scales calibrated every 6-12 months depending on the level of stress applied to them via use and environmental factors.
Non-legal trade scales
If you are not using your scales to determine how much someone should pay you, or in court or medical practice, you are not required to use a legal trade scale. Non-legal trade scales generally do not undergo the rigorous accuracy testing that legal trade scales do, which makes them cheaper, but also less trustworthy.
Non-legal trade scales can be used in industrial settings to:
- Monitor health of livestock
- Internal reporting
- Adhere to the load bearing capacity of a machine
Even if you are not legally required to use a legal trade scale, if you value accuracy in your measurements, Position Partners recommends using one. Using legal trade scales improve your reputation as an honest supplier, and improve your reporting. Even small industrial scale inaccuracies can build up, turning into big problems the more material is weighed on them. An inaccurate scale used over a reporting period can cause inaccurate balance sheets detailing a business’ overall output or productivity, which in turn causes inaccurate forecasts for your business.
Over time, scales become less accurate due to damage, environmental factors, or natural wear-and-tear. To keep your industrial scale accurate, and in the case of legal trade scales, compliant to NMI regulations, scales should be re-calibrated every 6-12 months or whenever they undergo major hydraulic work.
If scales are moved frequently, they should be calibrated more frequently. This is because the location of the scales determines how it is angled to “magnetic north” and its altitude to sea level, which both affect the acceleration of gravity that the scale is subject to. When a scale is calibrated to accommodate for the acceleration of gravity in one place, it may not accommodate for the acceleration of gravity in another, which makes it less accurate.
Source: Position Partners