36
SECTION 3, continued
3.1.11 Using the SAMPLE Key
Press the SAMPLE keytobegineditingthesamplenumbershownintheMode
display (green LED). The annunciator next to the key lights to indicate that the
SAMPLE mode is selected.
3.1.12 Using the SETUP Key
Press the SETUP key to begin editing the setup number to configure the instrument
for specific operational functions (e.g., keyboard beeper on or off, print interval,
date and time, signal averaging, etc.). After the setup key is pressed, pressing the
PRINT key prints a list of the setup numbers along with their setup commands.
3.1.13 Key Annunciator Tone (Beeper)
The key annunciator tone (beeper) is selectable on or off. When the mode is
selected on, each key press is acknowledged by an audible “beep.” The
instrument is shipped with the tone on. To turn the tone off or on, use the
following procedure:
Press the
SETUP key. The annunciator lights and one of the two small green LED
digits in the mode display begins to flash. If the display does not read
00,usethe
edit keys to select
00. Press ENTER. The display reads BEEP ON or BEEP OFF.
Use the up or down keys to display the desired operational mode. Press
ENTER to
accept the setting. Press
SETUP to exit the setup mode. Pressing UNITS/Exit at any
time, prior to accepting the new setting, exits the setup mode leaving original
setting intact.
3.2 Calibration
The electronic and optical design of the 2100AN Turbidimeter provides long-term
stability and minimizes the need for frequent calibration. The multi-detector
ratioing optical system compensates for electronic and optical system variations
between calibrations. When data is used for USEPA reporting, recalibrate at least
every 90 days, or as stipulated by the regulating authority.
Note: The calibration is based on a first order linear equation consisting of up to four
independent variables. Unpredictable results may occur if standards other than the
recommended calibration points are used. The factory suggested calibration points are
those determined by Hach Company chemists and engineers to provide the best
calibration accuracy. Use of Formazin standards other than those specified in
Section 3.2.3 may result in less accurate calibrations.
Note: Alternately, obtain optimum calibration accuracy using the StablCal
®
Calibration Kit
for the 2100AN Turbidimeter. Kit contains prepared, stabilized formazin suspensions of
<0.1-, 20-, 200-, 1000-, 4000-, and 7500-NTU. Order Cat. No. 26595-00 (500 mL each)
or Cat. No. 26595-05 (ampuled).
Periodically, as experience or regulating authorities indicate, verify the
instrument calibration using pre-calibrated Gelex
®
Secondary Standards (refer to
Section 3.2.5 on page 42). If the reading in the range of use is not within 5% of the
standard’s assigned value, recalibrate using Formazin primary standards (refer to
Section 3.2.4 on page 39).
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