Honeywell UDA2182 manual Procedure 14 Running a Probe Bias Scan, Step Action Screen Press

Input Calibration

exceeding 0.8 volts, a second process (water reduction) begins to occur and the current again rises. To achieve stable results, the probe should be operated within the flat region so that small changes in the probe characteristics result in negligible changes in probe current.

In some industrial wastewater applications, particularly those in petroleum refineries, active gases dissolved in the wastewater can cause this current-voltage characteristic to shift, moving the flat region to other, usually lower, voltages. Also, in some very rare instances, the chemical treatment of boiler water can cause this current-voltage characteristic to shift, moving the flat region to other, usually lower, voltages.

To summarize, the Probe Bias Test automatically varies the probe voltage while displaying the probe current as shown in the figure. At the completion of the test an opportunity to change the bias voltage is provided. Thus, even where significant gaseous contamination might otherwise interfere with the response of the probe to dissolved oxygen, this advanced feature allows the probe to operate.

(If the results of the probe bias test should ever be significantly different from those shown in the figure, Honeywell Service should be consulted.)

Procedure

Table 8-14 Running a Probe Bias Scan

Step		Action	Screen
1
	Press	Calibrate	CALIBRATION
			Input PV Cal
			Input Temp Cal
			Output Cal
			Cal History
2
	Press	Enter	PV INPUT CAL
			In 1 DO Cal

		Use		to select
		Input 1 or 2 DO Cal
3
	Enter	IN1 DO CAL
Press		Air Cal
		Sample Cal
		Reset Cal Factor
		Pressure Cal
		Pressure Offset
		Reset Prs	Offset
		Bias Scan
		Bias Volts
		Reset Bias Volts

174 UDA2182 Universal Dual Analyzer Product Manual January 2009