Hanna Instruments wm 8910 User Manual

2 9

2 8

For WM 8912 only:
ORP calibration is not required, however, you can check the correct
functioning of the ORP electrode by immersing it into a HI 7020
solution. The controller should read in the 200 to 275 mV range. If
necessary follow cleaning and maintenance procedures described on
page 40.

Make sure the HI 7637     conductivity probe is connected to the DIN

socket and the meter is plugged to the mains. The calibration should
be ideally performed at the temperature of the liquid that is being
controlled.

PROCEDURE:

• Ensure that the probe is connected to the meter securely by

aligning the pins with the socket, pushing the plug in and
tightening the threaded ring.

• Insert and screw the probe into the PVC

sleeve with the holes towards the top
(the end nearest to the cable).

• Turn the switch to the "MEASURE" posi-

tion.

• With the conductivity probe in air, adjust the "OFFSET" or "0mS"

trimmer.

SLOPE ADJUSTMENT:

• Rinse the electrode thoroughly in water

and immerse it in pH 4.01 (HI 7004)
or pH 10.01 (HI 7010) buffer solu-
tion.

Note: Use pH 4.01 if you are going to measure acidic samples or pH

10.01 for alkaline measurements.

• Stir the electrode and wait about

one minute before adjusting the
"SLOPE" or "pH 4" trimmer to
display pH 4.01 (or 10.01) on
the LCD if the temperature of the
buffer solution is at 25°C (77°F).
Otherwise, refer to the chart on
page 37 for appropriate buffer
value corresponding to the buffer
temperature temperature.

The pH calibration is now complete.

4 cm

(1

½

")

HI 7004

°C

Make sure a combination ORP electrode is connected to the BNC socket
and the meter is plugged to the mains.
• Turn the switch to the "MEASURE" posi-

tion.

• Immerse the electrode in HI 7020     ORP

solution.

• Adjust the slope trimmer until

an ORP value of between 200
mV and 250 mV is displayed.

Note: The ORP offset point is factory calibrated. You can however readjust

the offset by shorting the ORP input connector on the controller
and turning the offset trimmer if necessary to read 0 mV.

4 cm

(1

½

")

HI 7020