LaMotte 2020wi Portable Turbidity Meters - Manual (Page 47)

be the same whether it is called 0.00 NTU or 0.02 NTU. For design
simplicity the 2020we/wi uses the term turbidity-free water and the value
of 0.00 NTU.
 PREPARATION OF TURBIDITY-FREE WATER
A 0 NTU/FNU Standard (Code 1480) is included with the meter. An
accessory package (Code 4185) is available for preparing turbidity-free
water for blanking the meter and dilution of high turbidity samples.
The preparation of turbidity-free water requires careful technique.
Introduction of foreign matter will affect the turbidity reading. A fi ltering
device with a special membrane fi lter is used to prepare turbidity-
free water. The fi lter, fi lter holder and syringe must be conditioned
by forcing at least two syringes full of deionized water through the
fi ltering apparatus to remove foreign matter. The fi rst and second
rinses should be discarded. Turbidity-free water as prepared with the
following procedure may be stored in the dark at room temperature in a
clean glass bottle with a screw cap and used as required. The storage
container should be rinsed thoroughly with fi ltered deionized water
before fi lling. The water should be periodically inspected for foreign
matter in bright light.
1. Remove the plunger from
the syringe (0943). Attach
the fi lter to the bottom of the
syringe.
2. Pour approximately 50 mL
of deionized water into the
barrel of the syringe. Insert
the plunger. Exert pressure
on the plunger to slowly force
the water through the fi lter.
Collect water in the clean
storage container. Rinse walls
of the container then discard
this rinse water.
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Analysis