Conveyor
belt scales

Hardware performance verified under optimal factory conditions with a known material sample. Valid only within specified operating ranges at a constant flow rate for at least three belt revolutions or 10 minutes of continuous run time.

Governs U.S. commercial/legal-for-trade installations. Applies two primary classes:

• Class 0.25 (and unmarked systems): Material test tolerance of ±0.25% of test load.

• Class 0.1: Material test tolerance of ±0.1% of test load.

Note: NIST error propagation analysis indicates real-world end-to-end measurement tolerance typically approaches 0.5% when accounting for mass standards and field variables.

The international standard utilizing Classes 0.2, 0.5, 1, and 2. OIML ratings do not automatically convert to NIST Handbook 44 compliance.

• Belt width and trough angle (0°, 20°, 35°, 45°)

• Idler diameter, spacing, and profile

• Conveyor incline angle

• Available straight run length (distance from nearest load point, curve, or pulley)

• Conveyor drawings or photos of the intended weigh zone

• Material type, maximum lump size, and bulk density (lb/ft3\text{lb/ft}^3 lb/ft3 or kg/m3\text{kg/m}^3 kg/m3)

• Tonnage requirements: Minimum, Normal, and Maximum TPH

• Nominal belt speed (FPM or m/s) and drive type (Fixed-speed vs. VFD)

• Operating environment (wet, abrasive, corrosive, high-temp)

• Target accuracy percentage

• Operational status (Process Monitoring vs. Legal-for-Trade / NTEP)

• Required outputs (4–20 mA, Pulse, Relay) and Fieldbus protocol (EtherNet/IP, Modbus, etc.)

• Preferred calibration hardware (Test weights, roller chain, or material test setup)