Reading Modes; Apply Silicone Oil To A Sample Cell; Indexing A Single Cell - Hach 2100Qis User Manual

Reading modes

1. Push the UP or DOWN key to enter the Reading Options menu.
2. Select Reading Mode to select one of the following options:
Option Description
Normal The normal mode reads and averages three readings. The
(Default result is shown after the reading.
setting)
Signal The Signal Average mode compensates for reading
Average fluctuations caused by drifting of sample particles through
the light path.
The X-bar icon is shown on the display when signal
averaging is on.
The Signal Average mode measures 12 times and starts to
show the average after three readings. The final result is
the average of all 12 readings.
Rapidly The Rapidly Settling Turbidity (RST) mode calculates and
Settling continuously updates the turbidity reading of the sample to
™
Turbidity a confidence of 95%, based on the accumulated trend of
(RST) the real time measured values.
The RST mode is best used on samples that settle rapidly
and continuously change in value. The reading is based on
a correctly prepared sample that is homogeneous at the
beginning of the reading. It is best applied to samples that
are greater than 20 NTU. The sample must be mixed
thoroughly by inversion immediately before inserting it into
the meter.
The target icon is shown on the display when the Rapidly
Settling Turbidity is on.
The Rapidly Settling Turbidity reads and calculates five
readings while showing intermediate results.

Apply silicone oil to a sample cell

Sample cells and caps must be extremely clean and free from significant
scratches. Apply a thin coating of silicone oil on the outside of the
sample cells to mask minor imperfections and scratches that may
contribute to light scattering.
Note: Use only the provided silicone oil. This silicone oil has the same refractive
index as the sample cell glass.
1. Clean the inside and 2. Apply a small bead
outside of the cells and of silicone oil from the
caps by washing with a top to the bottom of the
laboratory glass cell.
cleaning detergent.
Follow with multiple
rinses with distilled or
demineralized water.

Indexing a single cell

Precise measurements for very low turbidity samples require the use of
a single cell for all measurements or optically matching the cells. Use
one cell to provide the best precision and repeatability. When one cell is
used, an index or orientation mark (other than the factory-placed
diamond) can be placed on the cell so it is inserted into the instrument
with the same orientation each time.
When using a single cell, make an index or orientation mark on the cell
as follows:
3. Use the provided
oiling cloth to spread
the oil uniformly. Wipe
off the excess so that
only a thin coat of oil is
left. Make sure that the
sample cell is almost
dry with little or no
visible oil.
Note: Store the oiling
cloth in a plastic
storage bag to keep the
cloth clean.
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