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Old June 19th, 2011, 08:09 AM   #1

jcp is offline
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How to calculate the Accuracy of Pressure Transmitter and rtd's

Hi friends;
I done the calibration of pressure transmitters and rtd's.
I give one example of data for both plz guide me how i calculate the accuracy of the transmitter and RTD's.
Pressure transmitter:
Range 0 to 200" w.c
signal applied reading
0 0
50 51
100 101
150 151
200 201
The error is 1"w.c how i calculate the accuracy?
RTD's example
32 32
100 101
150 152
200 203
Now how i calculate the RTD accuracy while i used PT100 RTD.
PLz help me?
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Old June 19th, 2011, 08:55 AM   #2
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For the pressure transmitter, the range is 0-200" for a span of 200".
An error of 1" over 200" is 1/200 or 0.5%

For the RTD, the range is 32-200 or 168
An error of 3 over a span of 168 is 3/168 or 1.8%
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Old June 19th, 2011, 09:24 AM   #3
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Just make sure that whomever you give the information to understands what you are giving them.

Other things that effect overall accuracy are temperature and hysteresis. Some manufacturers lump all effects into a single value, others list them all separately. Just make sure you give enough information with your accuracy so the person using it can use the information properly.
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Old June 19th, 2011, 11:54 AM   #4
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Accuracy = (Deviation / Span ) * 100
Deviation = Expected Value - Actual Value

Since you said "Transmitter" and "Data" be sure you differentiate between sensor values and analog output values. That and 5 point checks up and down and you should be good

Last edited by JoeFin; June 19th, 2011 at 11:58 AM.
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Old June 21st, 2011, 03:06 AM   #5

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calcs by danw are correct, however you also have the accuracy of the testsignal and its reading.
if you are using steaming water the pressure of the air is important, just like with pressure readings.
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