Hanna Instruments HI 255 User Manual

Page 8

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

secondary LCD.

If the reading is out of range, the closest full-scale value will be displayed

blinking on the primary LCD.

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

Automatic Temperature Compensation feature, connect and submerge the

HI 7662 temperature probe into the sample as close as possible to the

electrode and wait for a few seconds.

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 ºC or

the last temperature reading with the ºC tag blinking.

The temperature can now be adjusted with the ARROW keys

(from 10.0 ºC to 120.0 ºC).

mV/ORP MEASUREMENTS
An optional ORP electrode must be used to perform ORP measurements

(see Accessories).

Oxidation-Reduction Potential (REDOX) measurements provide the quantification

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.

Press RANGE to enter mV range.

Submerge the tip of the ORP electrode (4 cm/1½) into

the sample to be tested and allow a few seconds for the

reading to stabilize.

4cm

)

1/2

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