Emerson 1154, 00809-0100-4514 manual Calculate zero adjustment correction in terms of pressure

Reference Manual

00809-0100-4514, Rev BA January 2008

Rosemount 1154

1.Calibrate the unit per preceding section to output = 4 mA at –100 inH2O and 20 mA at 300 inH2O.

2.Calculate correction factor:

0.75 %

------------------------ × 1, 200 psi= 0.9% differential input

1,000 psi

3. Calculate zero adjustment correction in terms of pressure:

0.9 % × –100 inH2O = –0.9 inH2O

4. Convert pressure correction to percent of input span:

–0.9 inH2O

---------------------------------------------------------------= –0.225 % span

400 inH2O input span

5. Calculate correction in terms of output span (mA):

–0.225 % × 16 mA span = – 0.036 mA

6. Add the milliamp correction to the ideal zero output (4 mA). This is the corrected ideal zero output:

4.00 mA – 0.036 = 3.964 mA

7. Calculate full-scale adjustment correction in terms of pressure:

0.9% × 300 inH2O = 2.7 inH2O

8.Repeat step 4 with the results of step 7:

2.7 inH2O

---------------------------------------------------------------= 0.675 % span

400 inH2O input span

9. Repeat step 5 with the result of step 8:

0.675 % × 16 mA span = 0.108 mA

10. Add the mA correction to the ideal full-scale output (20 mA). This is the corrected ideal full-scale output:

20.00 mA + 0.108 mA = 20.108 mA

11. Readjust zero and span adjustments for corrected outputs:

3.964 mA at –100 inH2O

20.108 mA at 300 inH2O

There is an uncertainty of ±0.5 percent of input reading per 1,000 psi associated with the span correction.

Zero

Zero shift with static pressure is not systematic. However, if the calibrated range includes zero differential pressure, the effect can be trimmed out after installation and with the unit at operating pressure.

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