Rosemount 2081 pH, Инструкция по эксплуатации

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17
SECTION 5.0 START-UP AND CALIBRATION
5.1 GENERAL.
The sensor must be wired to the
transmitter for calibration. See the appropriate sen-
sor manual for additional instructions relating specif-
ically to the sensor.
5.2 TEMPERATURE CALIBRATION. For the most
accurate temperature compensation, the tempera-
ture reading may need adjusting. The following
steps should be performed with the sensor in a grab
sample or process of known temperature. Calibrate
at or near the process temperature for greatest
accuracy.
1. Depress and hold both push buttons simultane-
ously to enter the transmitter menu. The trans-
mitter will auto scroll through the menu items.
2. When the display shows “
tAdJ
”, release both but-
tons. The display will show the present tempera-
ture value in degrees Celsius with the last digit
flashing. The tenths digit will alternate between a
value and °C. (The temperature can only be stan-
dardized in °F by using the Model 275 for config-
uration).
3. Compare the displayed reading with a calibrat-
ed temperature reading device. If the reading
requires adjustment, proceed to step 4. Other-
wise, depress both push buttons briefly to
accept the displayed value.
4. Depress and hold push buttons #1 (scroll) and
#2 (shift) as needed to display the desired tem-
perature value.
5. Enter the correct value into memory by depress-
ing both push buttons briefly. The display will
return to displaying the present pH value.
5.3 BUFFER CALIBRATION. The two buffer calibra-
tion will calculate the slope (efficiency) of the pH
sensor. (Computed limits: 47.3 to 59.9 mV/pH).
1. Obtain two pH buffer solutions with values at
least two pH units apart. Unopened buffers have
a shelf life of about a year, and once opened,
should ideally not be reused because of possi-
ble contamination.
2. Depress and hold both push buttons to scroll
through the menu items to “
HoId
”, then release
both buttons to place the transmitter in hold sta-
tus (“
HoId
” will periodically flash). This will main-
tain the output at the last process value read by
the transmitter and activate the hold flag on the
middle right hand side of the display.
3. Remove the sensor from the process and clean
it if necessary. Shake the sensor down to
remove entrapped air bubbles from the meas-
urement tip.
4. Place the sensing portion of the pH sensor into
a beaker containing the first buffer solution.
5. Allow the pH reading to stabilize, note the sen-
sor temperature from the display submenu, then
note the value at the buffer at that temperature.
Buffer pH values of various temperatures are
located on most buffer bottles. For example, at
5°C (41°F) a typical buffer is 6.95 pH but at 25°C
(77°F) it is 6.86 pH. See
“Note on Buffers” on the
following page.
6. Depress and hold both push buttons to scroll
through the menu items to “
buF1
” then release
both push buttons. The display will show the pH
value currently in “
buF1
” memory.
7. Depress and hold push button #1 (scroll) then
#2 (shift) as needed to display the buffer1 pH
value.
8. Enter the buffer value (at the sensor tempera-
ture) into memory by depressing both push but-
tons briefly. The transmitter will memorize this
value but will not change the calibration until
buffer #2 is entered. The display will return to
reading the present pH value.
9. Remove the sensor from the buffer, rinse and
gently dry it.
10. Place the sensing portion of the pH sensor into
a beaker containing the second buffer solution.
11. Follow the instructions in steps 5 through 8 for
buffer 2 (“
buF2
”). After entering the “
buF2
” value
the transmitter will calculate the electrode slope
and standardize the reading.
MODEL 2081 pH SECTION 5.0
START-UP AND CALIBRATION