Determining Calibration Frequency - Emerson Rosemount 3051S Series Reference Manual

Rosemount 3051S Series
Determining Calibration
Frequency
4-4
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. Determine the performance required for your application.
2. Determine the operating conditions.
3. Calculate the Total Probable Error (TPE).
4. Calculate the stability per month.
5. Calculate the calibration frequency.
Sample Calculation
Step 1: Determine the performance required for your application.
Required Performance:
Step 2: Determine the operating conditions.
Transmitter:
Calibrated Span:
Ambient Temperature Change:
Line Pressure:
Step 3: Calculate total probable error (TPE).
2
TPE =  
ReferenceAccuracy
Where:
Reference Accuracy =
Ambient Temperature Effect =

 0.0125

------------------------------------ -

Span
(1)
Span Static Pressure Effect
0.1% reading per 1000 psi (69 bar)
(1) Zero static pressure effect removed by zero trimming at line pressure.
Step 4: Calculate the stability per month.
 
0.125

-------------------------------------- - % of span for 5 years
Stability
=
Span
Step 5: Calculate calibration frequency.

Req. Performance TPE
Cal. Freq. = ---------------------------------------------------------------------- -
Stability per Month
0.30% of span
3051S_CD, Range 2A [URL=250 inH
classic performance
150 inH O (374 mbar)
2
± 50 °F (28 °C)
500 psig (34,5 bar)
2
  
TemperatureEffect StaticPressureEffect
+ +
± 0.055% of span
 per 50 °F
URL

0.0625
+ =

=

0.05% of span at maximum span
=

URL
 
0.3% 0.112%
–
= ---------------------------------------------
0.0035%
Reference Manual
00809-0100-4801, Rev FA
October 2010
O(623 mbar)],
2
2
 = 0.112% of span
0.0833% of span

= 0.0035% of span per month

–
= 54 months