Hanna-instruments HI 9829 Manual de usuario descargar pdf (Pagina 21)

4.2 SENSOR PREPARATION / ACTIVATION

4.2.1 pH Preparation

Remove the shipping cap from the pH sensor. If the shipping cap does not

contain any liquid, pour HI 70300 into shipping cap, place it back on the

sensor and soak for at least 1/2 hour before use. If HI 70300 is not available,

pH 4.01 buffer may be substituted.

4.2.2 ORP Activation

For improved redox measurements, the surface of the sensor must be clean and

smooth. A pretreatment procedure should be performed to ensure quick re-

sponse.

The pretreatment of the sensor is determined by the pH and the ORP potential

values of the sample. Use the table below to determine the treatment required.

First locate the typical sample pH. If the corresponding ORP value (mV) is higher

than the values in the table below, an oxidizing pretreatment is necessary. If the

value is lower, a reducing pretreatment is necessary.

pHpH

mVmV

pHpH

mVmV

pHpH

mVmV

pHpH

mVmV

pH pH

mV mV

0 990 1 920 2 860 3 800 4 740

5 680 6 640 7 580 8 520 9 460

10 400 11 340 12 280 13 220 14 160

For reducing pretreatment: immerse the electrode for at least five minutes in

HI 7091.

For oxidizing pretreatment: immerse the electrode for at least five minutes in

HI 7092.

4.2.3 D.O. Sensor Activation

The D.O. probe is shipped dry. To prepare the sensor for use:

• Remove the black & red plastic shipping cap and discard.

• Insert the supplied O-ring in to the membrane cap.

• Rinse the membrane with some electrolyte solution. Refill with clean electrolyte.

Gently tap the black membrane cap to dislodge air bubbles. To avoid damag-

ing the membrane, do not touch it with your fingers or directly tap the mem-

brane.

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Hanna-instruments HI 9829 Manual de usuario Pagina 21