Hach 2100N Manuel D'utilisation De Base page 14

Manual or automatic ranging
The manufacturer recommends that ranging be set to automatic for most
measurements.
The setting can be changed at any time during sample measurement.
Push RANGE repeatedly to step the instrument from automatic ranging
to manual ranging and then scroll through the manual range settings.
The Manual Range light turns on when manual ranging is selected. The
Auto Range light turns on when automatic ranging is selected.
Notes:
• When manual ranging is selected, the display flashes all 9s when the
sample being measured is greater than the selected range. The
display flashes all 0s when the sample measured is less than the
selected range.
• When automatic ranging is selected, the display flashes 9s when the
sample is greater than the maximum range of the instrument. The
display flashes 9s when Ratio is off and the measurement is greater
than 40 NTUs (268 nephelos or 9.8 EBCs). Turn Ratio on to increase
the range.
• When automatic ranging is selected, the display flashes all 0s when
the measurement is less than the range of the instrument or a
negative value. Calibrate the instrument.
Signal averaging on or off
Signal averaging corrects for reading fluctuations that are caused by
random drifting particles in the sample. When signal averaging is on, an
average reading is calculated every 3 seconds and shown on the
display.The last ten measurements are used to calculate the average
reading.
The manufacturer recommends that signal averaging be on for most
measurements.
Push SIGNAL AVG to turn signal averaging on or off. The SIGNAL AVG
light turns on when signal averaging is on.
Push ENTER when signal averaging is on to erase data in the signal
averaging buffer and provide an immediate update on the display as
necessary. This is especially useful when measuring samples with large
differences in turbidity.
14 English
Ratio on or off
Ratio on provides very good linearity, calibration stability and a wide
measurement range. Ratio on helps correct for interference when color
is present in the sample that absorbs at the wavelength of incident light.
The manufacturer recommends that Ratio on be used for most
measurements. Ratio must be on to measure samples greater than
40 NTUs (268 nephelos or 9.8 EBCs).
Push RATIO to turn Ratio on or off. The Ratio light is on when Ratio is
on.
Notes:
• If the sample being measured is greater than 40 NTU (or equivalent)
and Ratio is off, the display will show 9s and the RATIO light will flash.
Push RATIO to turn Ratio on and remove the over-range condition.
• Measurements with Ratio on and measurements with Ratio off are
almost the same for turbidity measurements that are less than 40 NTU
if interferences caused by color or light absorbing particles are not
present.
Maintenance
D A N G E R
Multiple hazards. Only qualified personnel must conduct the tasks
described in this section of the document.
Clean the instrument
Keep the instrument clean to get continuous and accurate operation.
N O T I C E
Never use cleaning agents such as turpentine, acetone or similar products to
clean the instrument including the keypad.
1. Turn the instrument off and disconnect the power cord.
2. Clean the surface of the instrument with a soft, moist cloth and a
weak soap solution.
3. Dry the surface of the instrument with a lint-free cloth.