manufacturer :       Hach

model :                   IL 550

annotation :           Dokumente engl.

Overview of product and function

The IL550 TOC-TN/IL530 TOC-TN analyzer determines the total carbon content and total nitrogen content of aqueous samples. Samples are digested using thermocatalytic high-temperature oxidation in the presence of special catalysts.

The analyzer can determine the total carbon content of small amounts of solid samples with the help of the integrated solids module or by connecting an external solids module.

The analyzer can be used in the following applications:

•            Water treatment

•            Environmental monitoring

•            Power stations

•            Waste and soil

•            Research and training

System structure

The IL530 TOC-TN and IL550 TOC-TN analyzers are compact tabletop instruments. The main components are permanently built into the basic analyzer. Accessories and reagents are connected or made available to the basic instrument for the purpose of performing tests.

The analyzer is controlled and the measurement data are evaluated with the help of the OmniToc control and evaluation software, which is installed on an external PC.

All components of the analyzer that have to be used for operating or maintenance purposes are accessible through two doors on the front of the analyzer, the left removable side panel, or the top

left panel.

The analyzer consists of the following main components:

•            Components for sampling

•            Pneumatics/tubing system

•            Combustion system

•            Components for drying and purifying the measurement gas

•            Detectors

•            Display and operating elements, with connections

•            Electronics unit

•            Accessory modules

IL550 TOC-TN Components

Figure 4 through Figure 6 describe the component layout of the IL530 TOC-TN

1 Condensate pump

2 Halogen trap

3 Needle valve for setting the NPOC purge flow

4 Water traps

5 Phosphoric acid pump

6 Reagent bottle for phosphoric acid

7 Collector tray

1 Pneumatic assemblies for gas supply

2 Combustion system

3 TIC condenser module (coil condenser at the back)

Performance specifications

Digestion principle                     Thermocatalytic oxidation

Digestion temperature               Up to 950 °C (1742 °F)

Catalyst

For liquid samples                     Pt/A _l2 O ₃

For solids module (internal)       CeO ₂ (Special catalyst)

Measurement methods              TC, TIC, TOC (Difference method), NPOC, TNb (optional)

                                                  In accordance with:

TOC: DIN EN 1484, ISO 8245, EPA 415, ASTM D2579, DIN 38409 H3 TNb: DIN 38409 Part 27, DIN EN 12660

Carbon detection                       NDIR (in the IL550 TOC-TN coupled with VITA® method)

Nitrogen detection                      CLD, ECD

Sample volume                          50 µL to 500 µL

Particle tolerance                       In accordance with DIN EN 1484

                                                  Only for particle-tolerant syringes

Sample introduction:

For IL550 TOC-TN                     Direct injection through septum-free port

For IL530 TOC-TN                     Direct injection through port with septum

Gas supply                                 Synthetic air (hydrocarbon free) or oxygen (at least 99.995%)

( carrier gas/NPOC auxiliary       Admission pressure 4–6 bar

gas for injector port)

Gas consumption:

Total                                           Approximately 15 L/h, depending on measurement mode

Measurement gas flow              160 ± 3 mL/min

Purge flow                                  Approximately 50 to 160 mL/min

Measurement gas flow for internal solids

module (optional)                       400± 3 mL/min

Control/evaluation                      Real time graphs, status display during the analysis, graphic

(OmniToc control and               representation of the measurement results, printout of the

Evaluation software)                  results

Physical and environmental specifications

Width                                          512 mm

Height                                         540 mm

Depth                                         530 mm

Weight                                        28 kg

Operating requirements             10–35 °C (50–95 °F), max. 90% relative humidity (non-condensing)

Storage requirements                5–55 °C (41–131 °F), 10–30% (use desiccant)

Atmospheric pressure               0.7–1.06 bar

Additional technical data

Power requirement (two                 115 V, 50/60 Hz or 230V, 50/60 Hz

models , not user-

configurable )

Installation category                         II

Pollution degree                               II

Fuses                                               115 V: 50/60 Hz: T, 10A H, 250V (2), OR 230 V: 50/60 Hz: T, 6.3A H, 250V (2)

Average typ: power consumption    1000 VA

Interface to PC                                 RS232

Interference suppression                 Interference suppressed in conformity with EN 55022 class

( electromagnetic compatibility)        A and BMPT Vfg. 243/1991

Detectors

NDIR detector

The NDIR detector (Non-dispersive Infrared absorption detector) is located behind the right side panel of the analyzer. Gases with molecules that contain different types of atoms have specific absorbance bands in the infrared spectrum. If a beam of light is transmitted through a cell that contains gases in the infrared-active range, these gases absorb a fraction of the total light at their characteristic wavelengths. This fraction is proportional to their concentration in the gas mixture. The light receptors in the NDIR detector are selective for carbon dioxide. Two measurement channels are evaluated in parallel. Depending on the carbon dioxide content of the measurement gas, the measuring range is switched dynamically.

Processing measured values with the VITA method in the IL550 TOC-TN

The carbon dioxide molecules are measured for as long as they are present in the cell of the NDIR detector. Fluctuations in the measurement gas flow during the carbon dioxide measurement (e.g. from evaporation and condensation when liquid samples are injected) occasionally cause carbon dioxide molecules to be measured spectrometrically for a longer (lower gas flow) or shorter (higher gas flow) time.

The VITA method (retention time coupled integration for TOC analyses) measures the measurement gas flow in parallel to the NDIR signal. Fluctuations in the flow are compensated for by a computer-aided standardization of the NDIR signal to a constant

gas flow. Integration is performed after the NDIR signal is standardized. A highly accurate digital flow meter is installed beside the NDIR detector for this purpose.

Electrochemical NO detector (ECD, optional)

The electrochemical NO detector can be used to determine total bound nitrogen (TNb). The NO detector is behind the right side panel of the analyzer.

The NO detector analyzes the nitrogen oxide (NO) content of the carrier gas. The measurement gas formed by thermal oxidation of the sample enters the detector, where the nitrogen oxides in the gas diffuse through a highly selective membrane and into the electrochemical measuring cell. The nitrogen oxides undergo oxidation at the anode, causing a change in the current between the electrodes. This change is proportional to the concentration of the nitrogen oxides. The change in the current is evaluated as a signal and enables the nitrogen content of the sample to be determined (TNb determination). The electrolyte in the measuring cell serves only as a catalyst and is not consumed. A supply voltage is needed for the operation of the electrochemical NO detector.

A backup voltage (supplied by a U9VL ultra life battery) is needed to maintain the internal equilibrium of the ECD in the intervals between measurements (analyzer is switched off). The battery is located in the right side of the analyzer.

ChemiLuminescence detectors (CLD, optional)

TNb can also be determined by connecting a chemiluminescent detector to the analyzer. The CLD is an external add-on that stands to the right of the instrument (Appendix C ChemiLuminescence detector (CLD) on page 173).

The measurement gas formed by thermal oxidation of the sample is dried and then enters the reaction chamber of the

chemiluminescent detector, where the TNb is determined. The nitrogen monoxide in the measurement gas is oxidized by ozone to nitrogen dioxide. The excited nitrogen dioxide molecules emit light quanta (luminescence) as they revert to the energy ground state. The luminescence is measured with the help of a photomultiplier and is proportional to the nitrogen monoxide concentration. It can therefore be used to determine the total nitrogen content of the sample. The reaction chamber is maintained at a negative pressure in order to suppress quench effects.

Add-on options

Sampler

The ASX 60 sampler (Figure 26) is fastened to the basic instrument by means of four hexagon-socket screws. It is suitable for both homogeneous and inhomogeneous particle-containing samples. Each sample can be stirred individually just before the analysis. The stirrer speed can be selected manually. In the NPOC mode, the samples can be automatically acidified.

Integrated solids module

A special reactor and port with manual feed can be integrated into the combustion system of the analyzer to enable small quantities of solid samples to be analyzed (Figure 27). Digestion temperatures of up to 950 °C (1742 °F) can be reached. The digestion takes place in the presence of a catalyst.

External solids module

An external HSC solids module can be connected to the analyzer to enable solid samples to be digested at temperatures of up to 1300°C