Scale Inspection Program
Weighing device or "scale" inspections are conducted annually. The inspections are announced in order to increase their effectiveness in improving compliance with code requirements. All scales must be inspected if used commercially. This includes checkweighers. A paper seal is affixed to the scale - visible to the customer - if the scale accuracy is within tolerance.
Revised Code of Washington (RCW), Chapter 19.94 "Weights and Measures - 1969 Act"
Seattle Municipal Code (SMC) Chapter 7.04 - "Weights and Measures Code"
National Institute of Standards and Technology (NIST) Handbook 44 Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices (1997), Section 2.20 "Scales"
National Conference on Weights and Measures (NCWM) Publication 3 2nd ed. Policy, Interpretations, and Guidelines, Section 3 "Specifications, Tolerances and Device Inspections"
National Conference on Weights and Measures (NCWM) Publication 12 Examination Procedure Outlines for Weighing and Measuring Devices (December 1991)
State weights and measures inspectors test truck scales. These tests require special equipment.
Scales are inspected to insure that they are accurate for the services in which they are used, installed properly, and positioned so that customers can see the display. Accuracy tests include: (1) increasing and decreasing load tests, (2) shift tests, (3) zero return, and (4) repeatability.