Hanna Instruments HI 96741C Instruction Manual

14 15• Press RANGE/GLP/ to change the range.The range can be changed any time when theinstrument is inmeasurement mode.The selected range is memorized and the selectionremaines unchanged at power off or when thebattery is removed.Code ParameterP1 Total HardnessP2 Iron Low RangeThe HI 96741 can measure Free chlorine when range P1 is selected or Total chlorine whenrange P2 is selected. To change the active range follow the procedure:• Turn the meter on by pressing ON/OFF. Thedisplay briefly shows all tags on.• After startup, the range identification number isdisplayed on the secondary LCD as P1 or P2.RANGE SELECTIONSTARTUPPrepare the instrument for measurement as follows:• Unpack the instrument by removing the dust protection sleeve from the instrument cuvetteholder.• Place the battery in the instrument as described in the “BATTERY REPLACEMENT” chapter.• Place the instrument on a flat table.• Do not place the instrument under direct sun light.• It is important that the sample does not contain any debris.This would corrupt the reading.• Each time the cuvette is used, the cap must be tightenedto the same degree.• Whenever the cuvette is placed into the measurementcell, it must be dry outside, and completely free offingerprints, oil or dirt. Wipe it thoroughly with HI 731318or a lint-free cloth prior to insertion.• Shaking the cuvette can generate bubbles in the sample, causing higher readings. To obtainaccurate measurements, remove such bubbles by swirling or by gently tapping the cuvette.• Do not let the reacted sample stand too long after reagent is added, or accuracy will be lost.• It is possible to take multiple readings in a row, but it is recommended to take a new zeroreading for each sample and to use the same cuvette for zeroing and measurement.• After the reading it is important to discard immediately the sample, otherwise the glassmight become permanently stained.• All the reaction times reported in this manual are referred to 20°C (68°F). As a general ruleof thumb, they should be doubled at 10°C (50°F) and halved at 30°C (86°F).• In order to maximize accuracy, prior to a measurement follow the validation procedure tobe sure that the instrument is properly calibrated. If necessary, calibrate the instrument.