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Metrology: The Turtle of Engineering

10/14/2013 06:00 AM EDT
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MeasurementBlues
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Re:
MeasurementBlues   2/24/2014 4:55:26 PM
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For most calibrations to ahve any value, they need to be traceable to a national lab such as NIST (US), NPL (UK), or NRC (Canada). National lbas provide uncertaintly and confidence levels for equipment they calibrate. The equipment calibrated at a national las isusually a transfer standard that is then used to calibrate. equipment in a working lab.

See Follow the Chain to NIST-Traceable Calibrations

prabhakar_deosthali
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prabhakar_deosthali   10/15/2013 12:10:39 PM
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As long the sensors are analog, and the component values get affected by the ambient conditions , there will be need for calibration. However the reference equipment itself is subject to periodic calibration for which some absolute reference standards are required in the test and measurement lab.

DrQuine
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the importance of calibration
DrQuine   10/14/2013 10:32:23 PM
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Many people believe that modern digital equipment makes the need for calibration obsolete. They are wrong. I recently found a "currently calibrated" digital (long stem) thermometers that was reading 24.0 °F high, a digital logging thermometer that required a 13.0 °F offset to read correctly, and a digital scale that was reading 25 pounds off (on a 75 pound scale). If your team starts questioning instrument calibrations, push back.  If the measurement is worth making, it is worth making it correctly.

MeasurementBlues
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Re: like nasa
MeasurementBlues   10/14/2013 2:29:15 PM
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@Caleb, It's really when you're dealing with analog equipment. You can also substitute "unpredictable" for unproven. See Go inside Fluke's electrical metrology lab, from my visit there in 2012.

Caleb Kraft
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Re: like nasa
Caleb Kraft   10/14/2013 1:57:02 PM
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I was referring to new equipment (less than 10 years) being "unproven" as per the first paragraph. With how quickly tech advances I hadn't really thought about some of the slower sides. 

MeasurementBlues
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Re: like nasa
MeasurementBlues   10/14/2013 1:47:15 PM
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@Caleb, There is another issue relating to NASA and the military regarding calibration. These organizations have their own promary standards and calibratin procedures. There is debate in the calibration community about NIST traceability and is it necessary in some circumstances. In other words, should one accept measurement that may not be NIST traceable?

MeasurementBlues
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Re: like nasa
MeasurementBlues   10/14/2013 1:44:46 PM
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"I hadn't really thought about this from a callibration standpoint." What do mean by "this"? Are you referrng to long-lived equipment when the parts are unavailable.?

Caleb Kraft
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like nasa
Caleb Kraft   10/14/2013 11:31:28 AM
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That's interesting. I hadn't really thought about this from a callibration standpoint. It reminds me of the way NASA handles hardware.

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