Hanna Instruments HI 96761C Instruction Manual

Also see for HI 96761C: Instruction manual

Contents

71) GLP/ key2) CAL CHECK key3) ZERO/CFM key4) READ/ /TIMER key5) ON/OFF key6) Liquid Cristal Display (LCD)7) Cuvet alignment indicator8) Cuvet holderFUNCTIONAL DESCRIPTIONA microprocessor controlled special tungsten lamp emits radiation which is first opticallyconditioned and beamed to the sample contained in the cuvet. The optical path is fixed by thediameter of the cuvet. Then the light is spectrally filtered to a narrow spectral bandwidth, toobtain a light beam of intensity Io or I.The photoelectric cell collects the radiation I that is not absorbed by the sample and convertsit into an electric current, producing a potential in the mV range.The microprocessor uses this potential to convert the incoming value into the desired measuringunit and to display it on the LCD.The measurement process is carried out in two phases: first the meter is zeroed and then theactual measurement is performed.The cuvet has a very important role because it is an optical element and thus requires particularattention. It is important that both, the measurement and the calibration (zeroing) cuvets, areoptically identical to provide the same measurement conditions. Whenever possible use the samecuvet for both. It is necessary that the surface of the cuvet is clean and not scratched. This toavoid measurement interference due to unwanted reflection and absorption of light. It isrecommended not to touch the cuvet walls with hands.Furthermore, in order to maintain the same conditions during the zeroing and the measuringphases, it is necessary to close the cuvet to prevent any contamination.INSTRUMENT DESCRIPTION