32
5 - CALIBRATION
Martek Instruments, Inc.
and the "SPAN" prompt will be flashing.
5.3.2 pH Span Adjustment
After the pH sensor has been zeroed, the
span adjustment can be set. Remove the pH
sensor from the pH buffer 7.00 solution and
rinse it with fresh water. Using a light tis-
sue, gently pat the glass bulb of the pH elec-
trode removing observable moisture.
Place the pH sensor in pH buffer 4.00 or
10.00 solution depending upon the pH range
of the solution the sensor is to measure.
Choose the "SPAN" option by pressing the
SELECT
key. The display will prompt with
the following message:
Then will ask you to:
It may take several minutes for the volt-
age to stabilize. Once the displayed voltage
has stabilized, press the
SELECT
key. The
display will prompt with the following mes-
sage:
Input the pH value as a 4-digit number
(make sure you use the correct pH value cor-
responding to the temperature of the pH
buffer). You can alter the value of the flash-
ing digit by pressing the arrow keys up or
down. Move forward to the next digit by
pushing the
SELECT
key. Move back to a
previous digit by pushing the
EXIT
key. Once
the span point has been entered, the Mark 22
will automatically respond with the follow-
ing display:
and the "TIME" option will be flashing.
5.4
H
OW
TO
SET
D
ATE
AND
T
IME
The Mark 22 uses an internal clock to
maintain date and time for recording pur-
poses. This feature allows you to record ex-
actly when a measurement was made which
can facilitate on-line system performance
evaluations over a period of months or even
years.
To set the date and time, press the
SETUP
key and select the "CAL" option. Next, se-
lect the "TIME" option. The Mark 22 will
prompt with the following display:
and the "DATE" option will be flashing. Press
the
SELECT
key. The display will then indi-
cate the following:
The "mm" stands for month and the “dd”
stands for day. Alter the value of the flash-
ing digit by pressing the arrow keys up or
ZERO SPAN
pH
PLACE SENSOR IN
HI pH STANDARD
HIT KEY W/STABLE
+0.7120 VOLT
INP 4 DIGIT STD.
HI pH = 04.00
TEMP
COND
pH
TIME
DATE TIME
INPUT
mmdd
DATE
0101
