Hanna Instruments hi 221223 User Manual

8

• The pH is displayed on the primary LCD and the temperature on the

secondary LCD.

• The pH reading is out of range, the closest full-scale value will be displayed

blinking on the primary LCD.

• It is also possible to view the mV reading by pressing the RANGE key.

If measurements are taken successively in different samples, it is recommended

to rinse the electrode thoroughly with deionized water or tap water and then

with some of the next sample to prevent cross-contamination.
The pH reading is affected by temperature. In order to measure the pH

accurately, this temperature effect must be compensated for. To use the

Automatic Temperature Compensation feature, connect

and submerge the HI 7669/2W temperature probe into

the sample as close to the electrode as possible and wait

for a few minutes.
If the temperature of the sample is known, manual compensation can be

performed by disconnecting the temperature probe.
The display will then show the default temperature of 25 °C

or the last recorded temperature reading with the “°C”

symbol blinking.
The temperature can now be adjusted with the ARROW keys (from -20.0 ºC

to 120.0 ºC).

ORP  MEASUREMENTS
An optional ORP electrode must be used to perform ORP measurements (see

Accessories).
Oxidation-Reduction Potential (REDOX) measurements provide the quantifica-

tion of the oxidizing or reducing power of the tested sample.
To correctly perform a REDOX measurement, the surface of the ORP electrode

must be clean and smooth.
Pretreatment solutions are avaible to condition the electrode and speed up the

response time.