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MODEL 3081 pH/ORP SECTION 7.0
CALIBRATION OF pH MEASUREMENTS
SECTION 7.0
CALIBRATION OF pH MEASUREMENTS
7.1 General
7.2 Entering and Leaving the Calibrate Menu
7.3 Using the Hold Function
7.4 Temperature Calibration
7.5 Auto Calibration
7.6 Manual Calibration
7.7 Making the Transmitter Reading Match a
Second pH Meter (Standardization)
7.1 GENERAL
The Calibrate menu allows the user to calibrate the pH and temperature response of the sensor.
The transmitter does a two-point pH calibration. Both manual and auto calibration are available. In auto calibration the
transmitter automatically stores temperature-corrected calibration data once readings have met programmed stability lim-
its. In manual calibration the user enters buffer values and judges when readings are stable. The transmitter reading can
also be made to match the reading of a second pH meter.
Temperature calibration is a one-point standardization against a reference thermometer.
Prompts guide the user through the calibration procedures.
7.2. ENTERING AND LEAVING THE CALIBRATE MENU
Press CAL on the infrared remote controller (IRC) to enter the Calibrate menu. To store new settings in memory, press
ENTER . To leave the Calibrate menu without storing new values, press EXIT . Pressing EXIT with a prompt showing
returns the display to the first prompt in the sub-menu. Pressing EXIT a second time returns the transmitter to the process
display.
If program settings are protected with a security code, pressing PROG or CAL will cause the Id screen to appear. Key
in the security code and press ENTER . The first sub-menu will appear. For more information, see Section 5.7, Security.
A transmitter adjacent to the one being calibrated may pick up signals from the IRC. To avoid accidentally changing set-
tings, use a different security code for each nearby transmitter. See Section 5.7, Security, and Section 8.6, Display Units,
for details.
7.3 USING THE HOLD FUNCTION
During calibration, the sensor may be exposed to solutions having pH outside the normal range of the
process. To prevent false alarms and possible undesired operation of chemical dosing pumps, place the
transmitter in hold during calibration. Activating hold keeps the transmitter output at the last value or sends
the output to a previously determined value. See Section 8.3, Output Ranging, for details.
After calibration, reinstall the sensor in the process stream. Wait until readings have stabilized before
deactivating Hold.
To activate or deactivate Hold, do the following:
1. Press HOLD on the IRC.
2. The HoLd prompt appears in the display. Press Ï or
Ð
to toggle the Hold function between On and OFF.
3. Press ENTER to save.