Bulk flow meters are high-capacity, robust instruments designed to measure large volumes of liquids (such as petroleum, chemicals, and water) or solids in industrial,, this article from Alibaba.com indicates for custody transfer, inventory management, and loading operations. They typically offer high accuracy ($\pm$0.1% to $\pm$0.5%) using technologies like positive displacement,

• High Capacity: Designed for rapid measurement of high-volume flows.
• High Precision: Used for custody transfer, requiring accuracy within $\pm$0.1% to $\pm$0.5%.
• Robust Construction: Often made from stainless steel or aluminum to withstand harsh environments.
• Measurement Technologies:
  • Positive Displacement (PD) Meters: Commonly used for liquid fuels and oils, featuring rotating lobes or blades.
  • Electromagnetic/Radiometric Meters: Often used for non-metallic solids, powders, and grains.
  • Ultrasonic Meters: Used for large-scale water or gas, 

• Petroleum & Chemical Industry: Loading and unloading tankers (road/rail), aviation fueling, and bio-fuel preparation, and the Avery Hardoll/Sync Water Tech website.
• Water Management: Large-scale water distribution and leakage detection, 
• Industrial Processing: Measuring raw materials like powders, grains, and granulates in manufacturing, 

• Mechanical Meters: Traditional PD meters for high-accuracy liquid measurement.
• Digital/Smart Meters: Modern units with IoT capability for real-time monitoring, 
• Non-Contact Meters: Radiometric sensors that measure materials on conveyors without touching them, as explained on the Berthold Technologies