Rosemount 1054B - 4.6.1 pH Electrode Diagnostics Setup; 4.7 Temperature Compensation and Isopotential Point

MODEL 1054B pH/ORP SECTION 4.0
CONFIGURATION
4.6.1 pH Electrode Diagnostics Setup
1. Enter the Set Menu by pressing the ACCESS key
twice.
2. SCROLL (
é
) until InP appears on the display and
SELECT.
3. on or oFF will display. If necessary, SCROLL (
é
) to
the desired mnemonic then ENTER. on activates
the diagnostics features.
4. If oFF is entered you can press the ENTER key to
return to the main set menu or press the pH key to
read pH.
If on is entered, the display will show rES. Proceed
to Step 5.
5. SCROLL (
é
) to display rES, CAL, SHt, or OId, then
SELECT the desired item. rES is a read only func-
tion. If CAL, SHt, or OId is selected, the right most
digit of the Numeric Display will flash to indicate
that the value can be changed.
6. Use the SCROLL (
é
) and SHIFT (
ç
) keys to
change the value, if desired.
7. ENTER the value into memory.
8. Press ENTER to return to the main Set Menu.
4.7 SOLUTION TEMPERATURE COMPENSATION
AND ISOPOTENTIAL POINT (Model 1054B pH
only). Display Mnemonic iSO. Used for applications
where the process' isopotential point (iPH) and tem-
perature coefficient (tCO) are not standard. For normal
pH measurements these values should be: rPH = 7.00
(normal process pH), iPH = 7.00 pH, tCO = 0.00
pH/°C. These values should only be changed for spe-
cial applications .
Solution temperature compensation is designed to
correct for changes in the actual pH of a solution
caused by changes in dissociation with temperature.
During standardization (Section 5.4), if the sample pH
is greater than about 6.5 and the lab test is run at a
substantially different temperature than the process,
determine a value for tCO in pH/°C and enter that
value. The tCO should be determined over as narrow a
temperature operating range as possible.
The isopotential point is the pH value at which tem-
perature changes do not affect the pH reading.
The analyzer method requires the user to enter the
normal process pH (rPH) and the temperature coeffi-
cient (tCO), then the isopotential point (iPH) will be cal-
culated. Conversely, entering the normal process pH
and the isopotential point causes the temperature
coefficient to be calculated.
4.7.1 pH Measurement in High Purity Water with
Ammonia Present. The special characteristics of this
measurement require changing isopotential pH value
and temperature coefficient used by the Model 1054B
pH. The reference pH (rPH) is the user’s normal
process pH. The isopotential pH value (iPH) of high
purity water with ammonia is 16.84 pH. The tempera-
ture coefficient tCO is – 0.033 pH/°C.
4.7.2 Isopotential Point Set Up (iSO).
1. Enter Set Mode by pressing the ACCESS key
twice.
2. SCROLL (
é
) to display iSO and SELECT.
3. SCROLL (
é
) to the desired menu item and
SELECT. The Numeric Display will flash.
4. SCROLL (
é
) and SHIFT (
ç
) to display the
desired value and ENTER it into memory.
5. Repeat Steps 3 and 4 as required.
6. Press the ENTER key to return to the Set Menu.
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