14 15
pH CALIBRATION
For best accuracy, frequent calibration of the instrument is recom-
mended. The instrument should be recalibrated for pH:
a) Whenever the pH electrode or temperature probe is replaced.
b) At least once a month.
c) After testing aggressive chemicals.
d) Whenever the battery has been replaced.
e) When high accuracy is required.
PREPARATION
Pour small quantities of pH 7.01 (HI 7007) and pH 4.01 (HI 7004)
solutions into two clean beakers.
For accurate calibration use two beakers for each buffer solution: the
first one for rinsing the tip of the electrode, the second one for
calibration. This way, contamination of the buffers is minimized.
For accurate readings, use pH 7.01 (HI 7007) and pH 4.01
(HI 7004) if you are going to measure acidic samples, or pH 7.01
(HI 7007) and pH 10.01 (HI 7010) for alkaline measurements.
If you need to calibrate HI 8014 and HI 8915 to NBS standards,
use pH 6.86 (HI 7006) instead of pH 7.01 and pH 9.18 (HI 7009)
instead of pH 10.01.
PROCEDURE FOR HI 8014
• Remove the protective cap from the elec-
trode, rinse and immerse it in pH 7.01
buffer and stir gently. Wait a couple of
minutes for the reading to stabilize.
• Take the temperature of the buffer solu-
tion with a ChecktempC (or another
accurate thermometer), e.g. 20°C.
Note: The electrode should be submerged approximately 4 cm (1½")
into the solution. The ChecktempC should be located as close
as possible to the pH electrode.
°C
HI 7007
HI 7007
RINSE
HI 7007
CALIBRATION
• Set the rotary knob to °C position to display the manual
temperature setting and adjust the °C trimmer until the LCD
shows the measured temperature.
• Set the rotary knob to pH position to display pH measurement
and wait for the reading to stabilize and adjust the AP trimmer
with a small screwdriver until the LCD shows the pH value at the
above temperature (see page 18 for pH vs. temperature chart).
• Rinse and immerse pH electrode and
thermometer in pH 4.01 or pH 10.01
buffer (2
nd
calibration point); stir gently.
• Wait a couple of minutes, then adjust the mV/pH trimmer until
the LCD shows the pH value at the noted temperature (see page
18 for pH vs. temperature chart).
The pH calibration is now complete.
PROCEDURE FOR HI 8915
• First connect the pH electrode and the temperature probe to the
instrument, then switch it ON.
• Remove the electrode protective cap, rinse
the electrode tip with some pH 7.01
solution, then immerse the pH electrode
and temperature probe in a pH 7.01
buffer solution.
OFF
mV
°C
pH
ºC
OFF
mV
°C
pH
AP
pH
°C
HI 7004
pH
mV/pH
HI 7007
