Emerson Rosemount 4600 Reference Manual page 45

Reference Manual
00809-0100-4022, Rev GA
4.2.2 Determining calibration frequency
Calibration frequency can vary greatly depending on the application, performance
requirements, and process conditions. Use the following procedure to determine
calibration frequency that meets the needs of your application.
1.
2.
3.
4.
5.
Sample calculation
1.
Required Performance:
2.
Transmitter:
Calibrated Span:
Ambient Temperature
Change:
3.
TPE =
Where:
Reference Accuracy =
Ambient Temperature Effect =
Note
Temperature Effect is specified per 100 °F, divide by 2 for 50 °F temperature change.
4.
Stability = ±0.5% of span for 3 years = ±0.0139% of span per month
5.
Cal. Freq.
Operation and Maintenance
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Determine the performance required for your application.
Determine the operating conditions.
Calculate the Total Probable Error (TPE).
Calculate the stability per month.
Calculate the calibration frequency.
Determine the performance required for your application.
Determine the operating conditions.
Rosemount 4600G, Range 4
4000 psig
50 °F
Calculate total probable error (TPE).
2
( ) + (
ReferenceAccuracy TemperatureEffect
×
  per100°F
0.03 URL
± ------------------------------ -------------------------- -
+
1.0
 
Span
Calculate the stability per month.
Calculate calibration frequency.
(
–
Req. Performance TPE
---------------------------------------------------------------------- -
=
Stability per Month
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Operation and Maintenance
1.1% of span
2
)
= 0.572% of span
± 0.25% of span
= ±0.515% of span
2
) ( )
–
1.1% 0.57%
----------------------------------------- -
= =
36 months
0.0139%
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