Hach-Lange 2100P iso - Portable Turbidimeter Instrument - Manual (Page 21)

Section 2, continued
Page 21
4650098 operation.fm Calibration
2.3.2 Correcting for Turbidity of Dilution Water
The 2100P ISO Turbidimeter automatically compensates for turbidity contributed
by dilution water when calculating the true value of the lowest formazin standard.
Use high quality distilled or deionized water less than 0.5 FNU. The instrument will
display “E 1” after calibration if the dilution water turbidity is greater than 0.5 FNU.
In this case, prepare the water as directed below.
The value of the dilution water can be arbitrarily forced to zero using the calibration
procedure. This is not recommended for most applications and, if done, should be
done only if the dilution water turbidity is less than 0.2 FNU.
2.3.2.1 Preparing Dilution Water
Note: Use the same dilution water for all dilutions and the sample blank.
Collect at least 1000 mL of high quality dilution water (distilled or deionized water).
The 2100P ISO Turbidimeter, as received from the factory, is precalibrated and may
be used to check the dilution water turbidity. If the turbidity is greater than 0.5 FNU,
filter the water with the Sample Filtration and Degassing Kit (Cat. No. 43975-10) or
equivalent. When measuring low range turbidity, clean all glassware with 1:1
hydrochloric acid and rinse several times with dilution water. If the glassware is not
used immediately, use stoppers to prevent contamination from small particles.
2.3.3 Calibrating the Turbidimeter
NOTES
• If the
I/O
key is pressed during calibration, the new calibration data is lost and the
old calibration will be used for measurements. Once in calibration mode, only the
READ
,
I/O
, ×, and Ö keys function. Signal averaging and range mode must be sel-
ected before entering the calibration mode.
• If “E 1” or “E 2” are displayed, an error occurred during calibration. Check the
standard preparation and review the calibration; repeat the calibration if neces-
sary. Press
DIAG
to cancel the error message (E 1 or E 2). To continue without
repeating the calibration, press
I/O
twice to restore the previous calibration. If
“CAL?” is displayed, an error may have occurred during calibration. The pre-
vious calibration may not be restored. Either recalibrate or use the calibration as
is.