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Accuracy of a flow measuring instrument

  1. Oct 2, 2013 #1


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    I have an instrument whose spec. sheet mentions Accuracy as 2% of FSD.

    The scale runs from 0 to 1000 Litres per hour. Does this mean if I check the instrument versus a gold standard calibrating instrument at a flow of 500 Litres per hour (which is our typical flow) the absolute error can be as large as 2% of 1000? i.e. 20 Litres?

    If so, then the allowable error at 500 LPH nominal flow becomes 4%.

    Am I doing this right?
  2. jcsd
  3. Oct 3, 2013 #2
    Yes, your measurement accuracy is 500±20 LPH. There is usually also a relative error of ε%, so you measure (1+0.01ε)500±20

    If you have calibration equipment you can measure the error (with a certain accuracy) and correct for it (with a certain accuracy).

    If the error is allowable or not is up to you, I have no idea where the 4% comes from.
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