Emerson 3051S Especificações descarregar pdf (Página 78)

Reference Manual

00809-0100-4801, Rev FA

October 2010

Rosemount 3051S Series

4-4

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

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.

Required Performance: 0.30% of span

Transmitter: 3051S_CD, Range 2A [URL=250 inH

O(623 mbar)],

classic performance

Calibrated Span: 150 inH

O (374 mbar)

Ambient Temperature Change: ± 50 °F (28 °C)

Line Pressure: 500 psig (34,5 bar)

TPE = = 0.112% of span

Where:

Reference Accuracy = ± 0.055% of span

Ambient Temperature Effect =

Span Static Pressure Effect

(1)

(1) Zero static pressure effect removed by zero trimming at line pressure.

ReferenceAccuracy

TemperatureEffect

StaticPressureEffect

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 0.0035% of span per month==

Cal. Freq.

Req. Performance TPE–

Stability per Month

-----------------------------------------------------------------------

0.3% 0.112%–

0.0035%

--------------------------------------------- 5 4 m o n t h s===

1 2 ... 73 74 75 76 77 78 79 80 81 82 83 ... 239 240

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