Why read this article? If you use load cells, the chances are that someone is setting them up using a 2 point or 5 point span calibrations. This type of setup often has high errors. This article discusses a more accurate way to eliminate the majority of these errors. Morehouse goes on to explain what mV/V is and why using a calibration curve may be the most accurate method for displaying the results in engineering units such as lbf, kgf, N.
Several organizations and publications reference or insist on maintaining a 4:1 Test Uncertainty Ratio (TUR) without understanding the level of risk that they may be subjecting themselves to. The general thought is if the lab performing the calibrations has standards at least four times better then what they are calibrating that everything is good. This paper discusses TUR, PFA Risk, and why the location of the measurement matters. We will discuss two managed risk guard banding methods (5 & 6) found in the ANSI/NCSL Z540.3 Handbook. We will show that a 4:1 TUR is not enough and can result in a 50 % risk.
Want to learn more about force measurement errors and the impact the wrong adapters can have? The wrong adapters can produce measurement errors up to 20 times that of when the instrument was calibrated. This technical paper provides greater detail on adapters for compression and tension calibration of load cells, mini load cells, washer load cells, s-beam, tension links, multi-axis, hand-held for gauges and other force measuring instrumentation. It goes into detail about to improve your force calibrations with the proper adapters.
Morehouse has been performing both ASTM E74 and ISO 376 calibrations for more than fifteen years. We have been calibrating in accordance with the ASTM E74 standard since its introduction in 1974, and performing ISO 376 calibrations since sometime in early 2000. Until recently, we assumed that the rest of the world and force community knew that the standards were completely different and that either standard could not be substituted for another. This paper explains those differences in more detail.
Measurement decision risk as probability that an incorrect decision will result from a measurement. Are you telling your customers instrument passes without considering measurement uncertainty? If taken to court, are your measurement defensible? This paper examines the proper way to make statements of compliance.
Having troubles understanding measurement uncertainty and how to put together a budget? This paper examines all of the components required to put together a full calibration and measurement capability (CMC) reviewed by Accreditation Bodies for your scope. This is a guide to calculating force measurement uncertainties and was published in Cal Lab magazine.
Article written by Henry Zumbrun for Cal lab Magazine.
What you need to know about dual range calibrations. Article from Test Magazine May 2016 issue.
Article in test magazine from Oct-Nov 2015 issue.
Written and published in Cal Lab magazine April 2016