Field Inspection Manual — Non-Automatic Weighing Devices
Part 3, Section 5: STP-5: Visual Examination of the Indicating Element
Sections 3 and 30 to 38 of the Non Automatic Weighing Devices Specifications.
Indicating elements, either approved separately or as part of complete weighing devices, are evaluated by the Approval Service Laboratory (ASL) for compliance with the specifications.
The inspectors role in performing the visual examination of an indicating element is to ensure that it is approved, the value of the scale interval has been selected/set in accordance with the specifications or as specified in the Notice of Approval (NOA); that names, symbols and defining words are legible; and that the parts of mechanical indicating elements are in good working condition.
Values of "d" and "e"
The inspector must ensure that the value of "d" has been selected in accordance with the requirements prescribed by sections 3, 36, 37 and 38 of the specifications. The inspector must also ensure that the values of "d" and "e" meet the limitations laid out in the Notice of Approval. Namely, the maximum number of scale intervals (n max ) must not exceed the number authorized by the Notice(s) of Approval and the value of "e" selected must not be smaller than the minimum value (e min ) authorized by the NOA for the weighing element.
The inspector ensures that the unit(s) of measurement selected is (are) a legal unit of measurement and that the scale was approved for that unit.
Except for weight classifiers, the inspector must ensure that the value of the scale interval indicated and printed are the same.
Legible Symbols and Defining Words
The inspector ensures that defining words, symbols or abbreviations for weight and price values, and metrologically significant annunciators, are legible and that the display segments are in good condition.
Beam or Dial Scales
The inspector must ensure that graduation lines are legible and allow for accurate weight readings. The inspector also ensures that the indicating component (pointer) is firmly attached, can travel freely (does not touch the chart) and is positioned (relative to the beam or chart) to reduce the effects of parallax to a minimum.
The inspector ensures that the indicating beam is secured in place; that parts of the poise are not loose; that adjusting material in the poise is enclosed securely, firmly fixed in position and not in contact with the beam; and that the pawl (if any) holds the poise firmly in position without any appreciable movement.
The inspector ensures that the balance ball or other mechanical zero setting means is firmly held in position.
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