Full Calibration; Min/Max Calibration; Two Point Calibration - Fisher FIELDVUE DLC3010 Instruction Manual

Instruction Manual
D102748X012

Full Calibration

Field Communicator Configure > Calibration > Primary > Full Calibration (2-5-1-2)
Full Calibration operations compute the sensor gain and offset from two independent observations of process data
points. They are appropriate for cases where the two input conditions can be established relatively quickly in one
session.

Min/Max Calibration

The following procedure can be used to calibrate the sensor if the process condition can be changed to the equivalent
of a completely dry and completely submerged displacer, but the actual precise intermediate values cannot be
observed. (E.g., no sight glass is available, but the cage can be isolated and drained or flooded.)
Correct displacer information and the SG of the test fluid must be entered before performing this procedure. Capture
Zero can be performed at minimum buoyancy (or completely submerged in upper fluid) before peforming Min/Max
Calibration.
Follow the prompts on the Field Communicator to calibrate the instrument and sensor.
1. Set the control loop for manual control.
2. Enter the specific gravity for the liquid in the system.
3. Adjust the liquid level until the displacer is dry (or completely submerged in upper liquid). Allow the output to
settle, then acknowledge establishment of the minimum buoyancy condition to the system.
4. Adjust the liquid level until the displacer is completely submerged in the lower liquid. Allow the output to settle,
then acknowledge establishment of the maximum buoyancy condition of the system.
The sensor torque rate is calibrated. If the Capture Zero procedure was run at the minimum buoyancy (or completely
submerged in upper liquid) condition, the zero of the PV calculation will be correct also. Verify that the upper and
lower range values are correct and return the loop to automatic control.

Two Point Calibration

This procedure is usually the most accurate method for calibrating the sensor. It uses independent observations of two
valid process conditions, together with the hardware dimensional data and SG information, to compute the effective
torque rate of the sensor. The two data points can be separated by any span between a minimum of 5% to 100%, as
long as they remain on the displacer. Within this range, the calibration accuracy will generally increase as the
data‐point separation gets larger. Accuracy is also improved by running the procedure at process temperature, as the
temperature effect on torque rate will be captured. (It is possible to use theoretical data to pre‐compensate the
measured torque rate for a target process condition when the calibration must be run at ambient conditions.)
An external method of measuring the process condition is required. This procedure may be run before or after Capture
Zero. It adjusts the calculation gain only, so the change in PV output will track the change in input correctly after this
procedure. However, there may be a constant bias in the PV until the Capture Zero procedure has been run.
Follow the prompts on the Field Communicator to calibrate the sensor.
1. Put the control loop in manual control.
2. Adjust the process condition to a value near the top or bottom of the valid range.
3. Enter this externally measured process condition in the current PV units.
4. Adjust the process condition to a value near the bottom or top of the valid range, but at a position that is toward the
opposite end of the range relative to the condition used in step 2.
5. Enter this second externally measured process condition in the current PV units.
Configuration
October 2014
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