Hanna-instruments HI 9829 Manuel d'utilisateur télécharger pdf (Page 90)

The calibration solutions and displayed measurements are as ppm Ammonium-

nitrogen. Due to the space restriction of the display the unit of measurement

will be displayed as “ppmAm”

The ammonium sensor will last longer in colder clean waters than in severely

contaminated water or warmer waters. This is because the active chemicals

responsible for the ammonium ion sensitivity are leached out of the membrane

with continued exposure. As the sensor ages there will be a decreased sensitivity

until the sensor will no longer calibrate or operate properly. The lifetime of the

sensor depends greatly on deployment conditions.

Although HI 7609829-10 is selective toward ammonium ions, it also responds

to other ions which can interfere with the measurement. The ratio of interfering

ion to ammonium ion must be less than the ratio indicated below:

Sodium: 90

Potassium: 0.75

Calcium: 125

Magnesium: 4000

Exposure to these interferences does not cause permanent damage to the sensor.

Note that the potassium ion interference is the strongest, and its concentration

must be less than the ammonium concentration to have no effect.

HI 76098290-10 Ammonium ion sensor linearity @25°C

-100

-50

100

150

0.01 0.1 1 10 100 1000

log ppm NH

1 2 ... 85 86 87 88 89 90 91 92 93 94 95 ... 103 104

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Hanna-instruments HI 9829 Manuel d'utilisateur Page 90