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Field Inspection Manual — Non-Automatic Weighing Devices

Part 2, Section 3: IPO-3: Equal Arms Scales


Equal arm pan-over-beam and beam-over-pan scales used to weigh commodities in trade including precious metals.


Inspector's weight kit.

Note: Inspection of precious metal scale (Class II or Class I) requires the use of special accuracy test weights.


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


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


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
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