Hanna Instruments Thermometer HI 7034 Manuale Utente Scaricare il pdf (Pagina 13)

TEMPERATURE COMPENSATIONTEMPERATURE COMPENSATION

TEMPERATURE COMPENSATION

The conductivity of an aqueous solution is the measure of its ability to

carry an electrical current by means of ionic motion. The conductivity

invariably increases with increasing temperature. It is affected by the

type and number of ions in the solution and by the viscosity of the

solution itself. Both parameters are temperature dependent. The de-

pendency of conductivity on temperature is expressed as a relative

change per degree Celsius at a particular temperature, commonly as

percent/°C. Acids, alkalis and concentrated salt solutions have lower

values, typically 1.5%/°C. Since a small difference in temperature

causes a large change in conductivity readings particularly at high

and low temperatures, the readings are usually normalized at 25°C.

The HI8819 manually compensates for temperature differences with a

fixed ß at 2%.

The HI8820 automatically compensates for temperature differences

with a built-in NTC sensor circuitry. A knob is also provided to adjust

the temperature coefficient manually from 0% (without compensa-

tion) to 2.5% per degree Celsius.

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Hanna Instruments Thermometer HI 7034 Manuale Utente Pagina 13