Calculating the accuracy of industrial instrumentation loops?
Calculating the accuracy of industrial instrumentation loops?
(OP)
I need to determine the accuracy of some instrumentation loops (purity, flow, pressure, and temperature). My plan is to use the spec sheets to find the accuracy of each component in the loop and simply add them to get the total accuracy(inaccuracy). I was also going to assume no inaccuracies due to the installation. Is this valid?
Thanks and Regards.
Thanks and Regards.





RE: Calculating the accuracy of industrial instrumentation loops?
You may have noise between the sensor and the amplifier.
A loop with an integrator zeroes out the static errors
but not the dinamic ones.
The whole control loop has to be analyzed.
----------------------------
Please read FAQ240-1032: How to ask a meaningful question
My WEB: <http://geocities.com/nbucska/>
RE: Calculating the accuracy of industrial instrumentation loops?
Typically, RSS is used, i.e., root of sum of squares.
More precise approach is to develop the entire transfer function and use the partial derivatives as coefficients in the RSS.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Calculating the accuracy of industrial instrumentation loops?
RE: Calculating the accuracy of industrial instrumentation loops?
Mark Hutton
RE: Calculating the accuracy of industrial instrumentation loops?
Note that most manufacturers declare the instrument accuracy as based on calibration in their own laboratories under reference conditions and may not perform with the same accuracy under process conditions.
JMW
www.ViscoAnalyser.com
RE: Calculating the accuracy of industrial instrumentation loops?
Orifice flanges require a precise distance between flange taps. Use the wrong gasket and the distance is wrong. Head type meters require a fully developed flow profile. This is usually accommodated by adequate upstream and downstream straight pipe per standards. This may not eliminate swirl.
Impulse lines change the temperature of the fluid. Pressure instruments in gas service are sometimes mounted below the tap and collect condensate. The condensate provides extra pressure. This is significant if measuring 10 psig and less significant if measuring 1000 psig.