Raising the Standard: Legal-for-Trade Belt Weighing in North America By: CST (Control Systems Technology) with original article by the late Lorne Danielson, TD Micronic Since their invention in 1908, belt scales have become indispensable in bulk materials handling, evolving from mechanical devices to precision-engineered systems integrated with digital technologies. Today, with flowrates reaching thousands of tonnes per hour in high-value sectors like mining and ports, the demand for commercial certainty has made legal-for-trade belt weighing more important than ever. Global Certification for Commercial Integrity In global trade, where bulk shipments can exceed tens of millions of dollars, even a 1% discrepancy can result in six-figure losses. While legal-for-trade certification is about compliance, it’s also an important factor in protecting revenue, upholding commercial trust, and reducing risk. There are two major authorities for trade-approved scales in North America: · NTEP (United States) · Measurement Canada (Canada) The International Organization of Legal Metrology publishes model international technical recommendations and should be considered as they are intended to harmonize how countries specify, test, and approve instruments. Static scales have long been certified to 0.1% accuracy; however, belt scales operate under more dynamic conditions. They are continuously in motion, simultaneously processing weight and belt travel while the material passes by at up to 6 m/sec, and are subject to a variety of external factors that scale manufacturers must endeavor to accommodate. Belt scales have historically faced challenges in meeting such stringent standards, but recent regulatory advancements have begun to close this gap. Raising the Bar North American regulators have significantly tightened belt scale certification protocols. In 2006, Measurement Canada approved 0.1% accuracy certification under Article R174 for high-value materials, and in 2014, adopted OIML-aligned testing across a broader range of flow rates (down to 30%). In parallel, NTEP introduced multi-point flow testing requirements, enhancing
confidence in belt scale performance under real-world conditions. Changes by the NTEP and Measurement Canada address four areas:
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