Sometimes it is difficult for the layman to understand the terminology used in standards. For example, the ASTM E4, “Standard Practices for Force Verification of Testing Machines,” has been updated. This new 2013 Edition is used when calibrating things like scales and other measuring devices. The meaning of Force Verification is to confirm the accurateness of the measurement of what we would call “weight” (the force of gravity on an object.)
ASTM E4:2013 allows the user to verify testing machines (i.e. scales and guages) that apply and indicate force. What kind of equipment might that be? Materials testing machines and instruments of all types, production equipment with force or weight transducers, hardness, structural testing rigs, simulators, mechanical, electro-mechanical or hydraulic drives. The equipment works by either tension or by compression.
These machines may be used in a production line prior to shipment or in a research lab to measure material properties. One thing that users of all such machines must do is confirm the equipment meets NIST traceability requirements. Use of ASTM E4, in conjunction with ASTM E74 (for calibration), ensures that the force measuring system of a testing instrument is accurate under static or quasi-static conditions.
FYI: The document is co-numbered AASHTO T67, as the American Association of State Highway and Transportation Officials participates in it’s maintenance.
Another standard used for this application is the ISO 7500-1, “Metallic Materials – Verification of Static Uniaxial Testing Machines – Part 1: Tension/Compression Testing Machines – Verification and Calibration of the Force-Measuring System.” The document differs from the ASTM E4 in that it provides for several classes of accuracy (.5 to 3%). The ASTM offers just the 1% plus or minus variance. The ISO 376 is the calibration equivalent for the ASTM E74.
If you use ASTM Standards like this one, you may prefer to purchase the Redline Edition. This is a handy way to review the changes, since you’ll get 2 copies of the standard. One is the regular new edition — the other is the old edition with all the changes “marked up” clearly for you to see.
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