Emerson Rosemount 2051G - Determining Calibration Frequency; Trim the Pressure Signal; Sensor Trim Overview

48
Reference Manual
00809-0400-4101, Rev BA
Operation and Maintenance
January 2018
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 Rosemount 2051G
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 2051G, Range 1 [URL = 30 psi (2,1 bar)]
Calibrated Span: 30 psi (2,1 bar)
Ambient Temperature Change: ± 50 °F (28 °C)
TPE = = 0.307% of span
Where:
Reference Accuracy = ± 0.065% of span
Ambient Temperature Effect = ± (0.05% URL + 0.25% 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
0.125 URL×()
Span
------------ ------------- ------------ ---
% of span for 5 years 0.0021% of URL for 1 month±=±=
Cal. Freq.
Req. Performance TPE–()
Stability per Month
------------ ------------- ------------- ---------- ------------- -------
0.5% 0.307%–()
0.0021%
----------- ------------- ------------- ------- 92 xmonths===