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Reference Manual
00809-0100-4102, Rev AA
Section 5: Operation and Maintenance
May 2013
Operation and maintenance
Sample calculation for 2051
(0.04% accuracy & 5-year stability)
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.
5.3.3 Compensating for Span line pressure effects (range 4 and
range 5)
Rosemount 2051 Range 4 and 5 pressure transmitters require a special calibration procedure
when used in differential pressure applications. The purpose of this procedure is to optimize
transmitter performance by reducing the effect of static line pressure in these applications. The
2051 differential pressure transmitters (ranges 0 through 3) do not require this procedure
because optimization occurs at the sensor.
The systematic span shift caused by the application of static line pressure is -0.95% of reading
per 1000psi (69 bar) for Range 4 transmitters, and -1% of reading per 1000psi (69 bar) for Range
5 transmitters. Using the following procedure, the span effect can be corrected to ±0.2% of
reading per 1000 psi (69 bar) for line pressures from 0 to 3626 psi (0 to 250 bar).
Use the following example to compute correct input values.
Required Performance: 0.20% of span
Transmitter: 2051CD, Range 2 [URL=250 inH
2
O(623 mbar)]
Calibrated Span: 150 inH
2
O (374 mbar)
Ambient Temperature Change: ± 50 °F (28 °C)
Line Pressure: 500 psig (34,5 bar)
TPE = = 0.105% of span
Where:
Reference Accuracy = ± 0.04% of span
Ambient Temperature Effect =
Span Static Pressure Effect
(1)
=
(1)Zero static pressure effect removed by zero trimming at line pressure.
ReferenceAccuracy
2
TemperatureEffect
2
StaticPressureEffect
2
++
0.0125 URL
Span
------------------------------------------ 0.0625+
% per 50 °F 0.0833% of span=
0.1% reading per 1000 psi (69 bar) 0.05% of span at maximum span=
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
-----------------------------------------------------------------------
0.2% 0.105%–
0.0021%
--------------------------------------------- 45xmonths===