56
Reference Manual
00809-0100-4108, Rev CA
Operation and maintenance
March 2017
Operation and maintenance
5.4.2 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. 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 for Rosemount 2088
Step 1: Determine the performance required for your application.
Step 2: Determine the operating conditions.
Step 3: Calculate total probable error (TPE).
Step 4: Calculate the stability per month.
Step 5: Calculate calibration frequency.
5.5 Trim the pressure signal
5.5.1 Sensor trim overview
A sensor trim corrects the pressure offset and pressure range to match a pressure standard.
The upper sensor trim corrects the pressure range and the lower Sensor trim (zero trim)
corrects the pressure offset. An accurate pressure standard is required for full calibration. A
zero trim can be performed if the process is vented.
Required Performance: 0.50% of span
Transmitter: Rosemount 2088G, Range 1 [URL = 30 psi (2,1 bar)]
Calibrated Span: 30 psi (2,1 bar)
Ambient Temperature Change: ± 50 °F (28 °C)
TPE = = 0.309% of span
Where:
Reference Accuracy = ± 0.075% of span
Ambient Temperature Effect = ± (0.15% URL + 0.15% of span) per 50 °F = ± 0.3% of span
Static Pressure Effect = 0% (does not apply to in-line products)
ReferenceAccuracy()
2
TemperatureEffect()
2
StaticPressureEffect()
2
++
Stability
0.100 URL×()
Span
------------ ------------- ------------ ---
% of span for 3 years 0.0028% of URL for 1 month±=±=
Cal. Freq.
Req. Performance TPE–()
Stability per Month
------------ ------------- ------------- ---------- ------------- -------
0.5% 0.309%–()
0.0028%
------------ ------------- ------------ ------- 6 8 xmonths===
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