00809-0100-4835 Rev BD
3-17
High Static Line Pressure Zero
Correction for Differential Pressure
Transmitters (All Ranges)
Zero shift with static pressure is not systematic. However, the effect
can be eliminated during calibration. To trim out the zero error at high
static line pressure, perform the following:
1. If the calibrated range contains zero differential pressure:
a. Calibrate the pressure transmitter according to the
preceding sections.
b. Apply atmospheric line pressure with zero differential
pressure.
c. Record the output reading.
d. Apply the intended line pressure at zero differential
pressure.
e. Adjust the zero to match the reading obtained in step c.
2. If the calibrated range does not contain zero differential
pressure:
a. Calibrate the pressure transmitter to the intended span
using the Zero Based Calibration Procedure.
b. Apply atmospheric line pressure with zero differential
pressure.
c. Record the output reading.
d. Apply the intended line pressure at zero differential
pressure.
e. Record the output reading.
f. Subtract the reading in step e from the reading in step
c. Note the sign associated with the calculated value,
as the sign is maintained for the adjustment in step i.
g. Calibrate the transmitter to the zero elevated or zero
suppressed calibration using the Elevated or
Suppressed Zero Calibration Procedure.
h. For range code 4 and 5 only, correct for static pressure
span effect as described in Static Pressure Span
Correction for Range Code 4 and 5 DP Transmitters
i. At the LRV, with atmospheric line pressure applied,
adjust the zero by the amount calculated in step f.
Figure 3-11 outlines an example of a Zero Correction for High Static
Line Pressure for a transmitter with a non-zero based calibration.
Figure 3-11 – High Static Line
Pressure, Zero Correction Example
If -0.007 mA was calculated in step f and the LRV reads 4.002 mA,
adjust the zero until the LRV reads 3.995 mA. DO NOT ADJUST
THE SPAN. When static pressure is applied, the output should read
Linearity is factory optimized and requires no field adjustment.