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

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SECTION 1
1.1

Instrument Description

Note: Ratio on must be selected 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. Patents 4198161, 0363676, and 5604590
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GENERAL DESCRIPTION
The Hach Model 2100N Laboratory Turbidimeter (Figure 1) is designed for
measurement of turbidity from 0 to 4000 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 2.8 on page 29 for additional information.
The 2100N Laboratory Turbidimeter also provides direct display in units of
Nephelos (0–26800 Nephelos) and EBCs (European Brewery Convention,
0–980 EBCs). These units are displayed using the conversion factors of
6.7 Nephelos per NTU and 0.245 EBCs per NTU.
The microprocessor-based Model 2100N is designed for laboratory use, and
employs advanced optical and electronic design. The instrument operates on
115/230 Vac, and provides an RS232C output for connection to a printer,
datalogger or computer.
Accessory items supplied with the turbidimeter include seven sample cells, a set
®
of five Gelex Secondary Turbidity Standards including a stray light standard,
Formazin Primary Standard, a power cord, silicone oil, sample cell oiling cloth,
a dust cover, and an instrument manual.
The Model 2100N Laboratory Turbidimeter is a Nephelometer with the capability
to measure with either the Ratio on or Ratio off. The instrument meets the design
criteria of the United States Environmental Protection Agency (Method 180.1)
and is acceptable for compliance reporting.
The optical system* (shown in Figure 2) is comprised of a tungsten-filament
lamp, lenses and apertures to focus the light, a 90-degree detector, forward-scatter
light detector, and a transmitted-light detector.
The instrument permits turbidity measurements at less than 40 NTU to be
performed utilizing only the 90 degree scattered-light detector or using the
complete set of detectors (ratio). With the Ratio on, the instrument's
microprocessor uses a mathematical calculation to ratio signals from each
detector. The benefits of using Ratio on for measurements include excellent
linearity, calibration stability and the ability to measure turbidity in the presence
of color.
The optical system (shown in Figure 2) includes a 870 ±30 nm light emitting
diode (LED) assembly, a 90° detector to monitor scattered light, and an LED
monitor detector. The instrument measures turbidity of up to 1000 units using the
single 90 ° detector in FNU measurement mode.
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