Hach-Lange 2100 N Laboratory Turbidimeter User Manual - Manual (Page 31)

flow cell, put the glass flow cell in liquid detergent for 24 hours and
then rinse fully.
• When measuring many samples of different turbidity, measure the
samples in order of the cleanest (lowest turbidity) to the dirtiest
(highest turbidity) to prevent contamination from one sample to the
next.
• Do not use greater than the recommended maximum sample pressure
of 34 kPa (5 psig).
• Keep the drain tubing below the center line of the instrument. If the
whole 152 cm (60 in.) length of drain tubing is used, make sure that
the end of the drain tubing is at least 46 cm (18 in.) below the center
line of the instrument.
Flow cell storage
• Install the reservoir cover when the system is not in use to prevent
contamination of the system by airborne particles.
• For short-term storage (a few hours), flush the system with distilled or
deionized water and leave the flow cell full of the flush water to
minimize air locks and build up of residue on the parts.
• For long-term storage, disassemble, fully clean and air dry all parts.
Using a manual flow cell
To set the flow rate, increase the height of the collection drain assembly
on the support rod to decrease the flow rate. Make sure that the bottom
of the collection drain assembly is no lower than 7.5 cm (3 in.) above the
support stand base.
To flush the flow cell, lower the collection drain assembly to the support
stand base to flush the flow cell.
Use a cell adapter
Many different test tubes, sample cells and ampules can be used to
measure samples when a cell adapter is used. Use a cell adapter when
the test tube, sample cell or ampule is less than 25 mm. Refer to
Accessories on page 40 for the available cell adapters.
Use only test tubes and sample cells that are free of significant
scratches. Clean and apply silicone oil to all sample cells, test tubes and
ampules used with the cell adapters. Refer to
Clean the sample cell
on page 17.
Note: Performance specifications may be different than shown in Specifications
on page 5 when test tubes, sample cells or ampules less than 25 mm are used.
Use a cell adapter when:
• Only a small quantity of sample is available.
• The sample to be measured is in an ampule that cannot be opened.
Refer to Table 3 for minimum sample sizes.
Table 3 Minimum sample sizes
Test tube size Sample
12 mm 2.5 mL
13 mm 3.5 mL
16 mm 5 mL
19 mm 7 mL
Install a cell adapter
1. Align the tab on the cell adapter toward the front of the instrument
( Figure 9 ).
2. Put the cell adapter in the sample cell holder.
3. Calibrate the instrument each time the sample cell diameter is
changed. Calibrate using sample cells of the same path length as the
sample cell that will be used to measure samples.
Note: If test tubes are taller than the cover for the sample cell compartment,
use the tall light shield provided with the cell adapter.
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