Emerson Rosemount 2088 Reference Manual page 63

Section 5: Operation and Maintenance
March 2014
Figure 5-1. Local configuration button options
A. Local Operator Interface - green retainer
B. Digital Zero Trim- blue retainer
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.
2.
3.
4.
5.
Sample calculation for Rosemount 2088
Step 1: Determine the performance required for your application.
Required Performance:
Step 2: Determine the operating conditions.
Transmitter:
Calibrated Span:
Ambient Temperature Change:
Step 3: Calculate total probable error (TPE).
TPE =
Where:
Reference Accuracy =
Ambient Temperature Effect =
Step 4: Calculate the stability per month.
Stability
54
A
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.
2
  
ReferenceAccuracy + TemperatureEffect
  
0.100 URL

-------------------------------------- - % of span for 3 years
=
Span
0.50% of span
Rosemount 2088G, Range 1 [URL = 30 psi (2,1 bar)]
30 psi (2,1 bar)
± 50 °F (28 °C)
2 2
  
= 0.309% of span
+ StaticPressureEffect
± 0.075% of span
± (0.15% URL + 0.15% of span) per 50 °F = ± 0.3% of span

= 0.0028% of URL for 1 month
Reference Manual
00809-0100-4108, Rev BA
B
Operation and maintenance