Section 1 General Description; Instrument Description; Standard Accessories; Principle Of Operation - Hach 2100AN Instrument Manual

SECTION 1

1.1 Instrument Description

Note: Ratio must be on for
measurement of samples greater
than 40 NTUs, 268 Nephelos and
9.8 EBCs.

1.2 Standard Accessories

1.3 Principle of Operation

* U.S. patent 4,198,161.
GENERAL DESCRIPTION
The Hach Model 2100AN Laboratory Turbidimeter measures turbidity from 0 to
10,000 NTU (Nephelometric Turbidity Units) with automatic range selection and
decimal point placement. Measure solutions with higher turbidity levels by
dilution with filtered sample and a simple calculation. Refer to Section 2.3.7 on
page 26 for additional information.
The 2100AN Laboratory Turbidimeter also displays in units of Nephelos
(0-67,000 Nephelos), EBCs (European Brewery Convention, 0-2,450 EBCs),
% Transmittance, Absorbance or Color Units (APHA Pt-Co Method). In addition,
two Application Specific Calibrations may be specified by the analyst. The
Application Specific mode uses the Nephelometric optical system in the same
manner as the NTU measurement mode. Special method development and sample
characterization also can be accomplished using the signal output from any of the
four detectors (see Instrument Setup for more information).
The microprocessor-based Model 2100AN is designed for laboratory use, and
employs advanced optical and electronic design. The instrument operates on
115/230 Vac, and provides a built-in printer, an RS232 output for connection to a
printer, data logger or computer, and a recorder output.
Accessory items supplied with the turbidimeter include six sample cells, a set of
®
six Gelex Secondary Turbidity Standards including a stray light standard,
7500-NTU Formazin Standard Ampule, a power cord, silicone oil, sample cell
oiling cloth, a dust cover, 2 rolls of printer paper and an instrument manual.
The Model 2100AN Laboratory Turbidimeter is a nephelometer with the
capability to measure in either Ratio on or Ratio off mode. The instrument meets
the design criteria of the United States Environmental Protection Agency (Method
181.1), and is acceptable for compliance reporting.
The optical system* (shown in Figure 1) is comprised of a tungsten-filament lamp,
lenses and apertures to focus the light, a 90° detector to monitor scattered light,
a forward-scatter light detector, a transmitted-light detector, and a back-scatter
light detector.
The instrument measures turbidity at less than 40 NTU using only the 90 degree
scattered-light detector or using the complete set of detectors (ratio). If the Ratio
mode is on, the instrument's microprocessor uses a mathematical calculation to
ratio signals from each detector. The benefits of using the Ratio mode for
measurements include excellent linearity, calibration stability, wide measurement
range, and the ability to measure turbidity in the presence of color.
11