Part 2, Section 3: IPO-3: Equal Arms Scales
Application
Equal arm pan-over-beam and beam-over-pan scales used to weigh commodities in trade including precious metals.
Equipment
Inspector's weight kit.
Note: Inspection of precious metal scale (Class II or Class I) requires the use of special accuracy test weights.
Use
Device is approved for trade use: NoA, Act Section 8
Device is suitable for the actual use: STP-1
Device has been initially inspected (if applicable) and bears the initial verification marks: R.29
Total capacity of weights does not exceed the scale capacity
Visual Examination — Installation and Location: STP-7
Device is installed in accordance with restrictions and conditions listed in the notice of approval and in accordance with manufacturer's instructions
Device is adequately supported
Device indicating and load receiving elements are positioned for customer's view (if applicable)
Clearance around load receptor
Device is properly leveled
Device is adequately protected
Visual Examination — Marking: STP-3
Device is marked with the required information
Marking is located as required
Marking is permanent (if applicable)
Marking plate is permanently attached to the device
Visual Examination — Indicating element: STP-5
Weight values are adequately defined
Scale marks and pointers are in proper condition
Material for adjusting zero is enclosed and secured
Balancing ball is in good condition and secured in place
Performance
Load Discrimination Test (No Load): STP-14
Increasing Test: STP-13
Eccentricity Test (not required on beam-over-pan scales): STP-15
Load Discrimination (Max): STP-14
Decreasing and Return-to-Zero Test: STP-13
Repeatability Test: STP-16
Trade Weights
Calibration of Counterpoise & Other Trade Weights: STP-29
Revision
Rev. 2
- add STP-29 reference for Trade Weights
- remove trade weight examination & calibration procedures from IPO
Rev. 1
- Reference to Appendix C for appropriate standards