Hach-Lange 2100 AN IS Laboratory Turbidimeter User Manual - Manual (Page 40)

Table 6 Formazin standard preparation (continued)
Standard Step 1 Step 2 Step 3
1000 NTU Add 50 mL of dilution
water to a clean 100-
mL class A volumetric
flask.
With a TenSette 1
Pipet, add 25.00 mL
of well-mixed 4000-
NTU formazin stock
solution to the 100-
mL flask.
Dilute to the mark
with dilution water.
Stopper and mix.
4000 NTU Rinse a clean sample
cell two times with well-
mixed 4000-NTU
formazin stock solution.
Put about 30 mL of
4000-NTU formazin
stock solution in the
sample cell. No dilution
is necessary.
— —
7500 NTU The 7500-NTU
formazin standard is
provided in an ampule
and is ready for use.
Refer to
Accessories
on page 46. Do not
open the ampule or
use the contents as
dilution stock. The
7500-NTU formazin
standard is stable for
up to one year.
— —
1 A class A volumetric pipet may be used in place of a TenSette Pipet.
Calibration notes
• Make sure that the instrument is in the same ambient conditions as
where it is used.
• Make sure that the standards are at the same ambient temperature as
the instrument before use.
• Use only the provided silicone oil. This silicone oil has the same
refractive index as the vial glass and masks minor glass differences
and scratches.
• Store the oiling cloth in a plastic storage bag to keep the cloth clean.
• If power is lost during calibration, the new calibration data is lost and
the last calibration data is used. To exit a calibration and not save the
new values, push UNITS/Exit.
• In Calibration mode, automatic range and signal averaging on are
selected. When calibration is completed, all operational modes go
back to the last settings.
• All nephelometric (turbidity units of measure) calibrations are done at
the same time.
• Ratio-on and Ratio-off calibration data is measured and recorded at
the same time.
• The 4000-NTU and 7500-NTU standards do not have to be measured
during calibration if FNUs will be measured. Push CAL/Zero after the
1000 NTU standard is measured to complete the calibration
procedure.
• The 7500-NTU standard does not have to be measured during
calibration if turbidity less than 4000 NTU will be measured. Push
CAL/Zero after the 4000 NTU standard is measured to complete the
calibration procedure.
• The FNU values of StablCal standards and formazin standards are
calculated using the conversion factors of 1 FNU = 1 NTU.
38 English