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SECTION 2, continued

2.4.2.4 Preparing Formazin Dilutions (Factory recommended)

Use 20, 100, and 800 FNU formazin standards for calibrating the

2100P ISO Turbidimeter. Dilutions with other FNU values can be

prepared and used (see Section 2.4.3.1 on page 30). If problems occur

when using alternate solutions, use the dilutions specified here.

Prepare all formazin dilutions immediately before use and discard after

calibration. The 4000 FNU solution is stable for up to a year, but

dilutions deteriorate more rapidly. Use the same high quality water

(turbidity <0.5 FNU) for the dilutions and the blank.

1. Attach the syringe

to the 3-way valve by

gently twisting the

square end into the

syringe tip. Attach the

connector, tubing and a

0.2 micron filter (clear

part faces syringe) as

shown. Be sure the

connections are tight.

2. Fill a beaker or

container with the water

to be filtered. Insert the

tubing into the container.

Slowly draw the 50 mL

of water into the syringe

by pulling up on the

syringe plunger.

3. Slowly push on the

plunger to force the

water through the filter

and into a graduated

cylinder or volumetric

flask. Repeat Steps 1–3

until the desired amount

of water is obtained.

Note: As the filter clogs, it

gets more difficult to push

water through it. Discard the

filter and attach a new filter.

Hach 2100P ISO User Manual

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