Emerson Rosemount 3051 CF Series, Reference Manual

Page: 95 / 146

For transmitters that are field installed, the manifolds discussed in Manifold operation
allow the differential transmitter to be zeroed using the zero trim function. Manifold
operation discusses both three-valve and five-valve manifolds. This field calibration
eliminates any pressure offsets caused by mounting effects (head effect of the oil fill) and
static pressure effects of the process.
Determine the necessary trims with the following steps.
Procedure
1. Apply pressure.
2. Check the pressure, if the pressure does not match the applied pressure, perform a
sensor trim.
See
Perform a calibration or sensor trim .
3. Check reported analog output against the live analog output. If they do not match,
perform an analog output trim.
See
Performing digital-to-analog trim (4-20 mA output trim) .
5.3.2 Determine calibration frequency
Calibration frequency can vary greatly depending on the application, performance
requirements, and process conditions. To determine calibration frequency:
Procedure
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 3051 (0.04 percent
accuracy and five-year stability)
The following is an example of how to calculate calibration frequency.
Procedure
1. Determine the performance required for your application.
Required Performance: 0.20% of span
2. Determine the operating conditions.
Transmitter Rosemount 3051CD, Range 2 [URL=250 inH
2
O
(623 mbar)]
Calibrated span 150 inH
2
O (374 mbar)
Ambient temperature change ± 50 °F (28 °C)
Reference Manual Operation and maintenance
00809-0100-4774 July 2020
Reference Manual 95